WORKS   BY    T.    MITCHELL    PRUDDEN,    M.D. 

The  Story  of  the  Bacteria,  and  Their 
Relations  to  Health  and  Disease 

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G.  P,  PUTNAM'S  SONS 

LONDON  NEW  YORK 


The 

Story  of  the  Bacteria 

And  their 

Relations  to  Health  and    Disease 

By 

T.  Mitchell  Prudden,  M.D. 


SECOND  EDITION,  REVISED  AND  ENLARGED 

ILLUSTRATED 


THE 

UNIVERSITY 

OF 


G.  P.  Putnam's  Sons 

New  York  and  London 
IRnfcfcerbocfcet 
1910 


COPYRIQHT,  1889 

BY 

T.   MITCHELL  PRUDDEN 
COPYRIGHT,  1910 

BY 

T.  MITCHELL  PRUDDEN 


Ube  ImCcfeerbocfcer  preaa,  flew 


' 


;.vo 

BIOLOGY 

LIBRARY 

G 


PREFACE 

TO  THE  FIRST  EDITION 

THE  bacteria  are  so  often  nowadays  the 
subject  of  discussion  and  discourse;  so  much 
which  is  at  once  disquieting  and  untrue  is  said 
about  them,  and  they  are  withal  of  such  prac- 
tical importance  to  the  health  and  well-being 
of  everybody,  that  it  has  seemed  to  the  writer 
worth  while  to  bring  together  in  some  simple 
fashion  a  little  of  our  knowledge  about  them. 

The  aim  then  of  this  book  is  to  present 
some  facts  from  a  small  corner  of  the  domain 
of  Science  in  such  form  as  will  be  plain  to  the 
unscientific,  and  with  these  some  extracts  from 
the  lore  of  the  physician  which  will,  it  is 
hoped,  be  both  interesting  and  useful  to  the 
lay  reader. 

T.  M.  P. 


307119 


PREFACE 

TO  THE  SECOND  EDITION 

SOME  twenty  years  ago,  when  the  first 
edition  of  this  little  book  was  issued,  bac- 
teriology was  in  its  early  infancy.  It  is  an 
infant  still,  but  grown  more  lusty  and  articu- 
late. These  minute  plants,  the  bacteria, 
logically  belong  in  the  purlieus  <jf  the  botanist. 
But  he  has  always  turned  the  cold  shoulder  to 
them. 

So  at  first  they  were  popularly  regarded  as 
the  foster  children  of  Medicine.  But  little  by 
little,  the  arts  and  the  industries  and  the 
farmer  have  found  them  out  so  that  to-day 
this  modest  bailiwick  of  the  biological  sciences, 
which  we  call  bacteriology,  is  held  in  trust 
by  a  syndicate  of  scientific  folk,  of  whom 
the  medical  men  are  perhaps  the  most  con- 
spicuous. 

Our  tread  along  the  pathways  which  bac- 
teriology opened  has  become  firmer  as  the 


vi  Preface 

years  have  passed,  and  out  of  its  revelations 
we  have  won  treasures  of  knowledge,  of  in- 
sight, and  practical  beneficence  to  man,  which 
lie  far  beyond  even  the  dreams  of  an  earlier 
day. 

While  the  revision  of  the  book,  for  this 
second  edition,  has  been  everywhere  exten- 
sive, the  greater  changes  and  additions  have 
been  made  in  the  sections  relating  to  disease 
and  its  prevention. 

The  addition  of  pictures  and  the  enlarged 
scope  of  the  book,  it  is  hoped,  will  make  it 
useful  to  the  new  generation  of  readers, 
whose  outlooks  for  increased  efficiency  and 
happiness  in  life,  is  curiously  interlinked  with 
the  performances  of  these  invisible  earth 
neighbors  of  ours,  whose  story  is  here  briefly 
rehearsed.  T.  M.  P, 


CONTENTS 

CHAPTER  PAGE 

I. — THE    CELLS   OF   THE    HUMAN    BODY — WHAT 

THEY  ARE  AND  WHAT  THEY  Do                .              .  I 

II. — BACTERIA  AND  SOME  OF  THE  THINGS  WHICH 

THEY  Do         .          .          .          .          .          .14 

III. — How  THE  BACTERIA  ARE  STUDIED          .          .  28 

IV. — SOME  BACTERIAL  CURIOSITIES       ...  43 

V. — AGRICULTURAL  CONJURERS                     ,         .  55 

VI. — BACTERIA  AS  MAN'S  INVISIBLE  FOES     .          .  60 

VII. — THE  BACTERIA  OF  WOUNDS  AND  OF  SURGICAL 

DISEASES         ......  70 

VIII. — THE  BACTERIA  OF  CONSUMPTION  OR  TUBER- 
CULOSIS .......  83 

IX. — TYPHOID  FEVER  AND  ITS  RELATIVES      .          .  100 

X. — ASIATIC  CHOLERA        .         .         .         .         .109 

XI. — PNEUMONIA,  INFLUENZA,  AND  COLDS     .  115 

XII. — DIPHTHERIA  AND  TETANUS            .         .         .  125 

XIII. — A  ROUND-UP  OF  UNDESIRABLES    .         .         .  131 

XIV. — SAFEGUARDS  OF  THE  BODY  AGAINST  DISEASE.  141 

XV. — How  SCIENCE  HELPS  THE  BODY  IN  INFECTION  155 


Contents 

CHAPTER  PAGE 

XVI. — THE   COMMON   SOURCES   OF   BACTERIAL   IN- 
FECTION .         .         .         .         .         .175 

XVII. — WATER  AND  ICE  AS  SOURCES  OF  INFECTION     184 

XVIII. — HAZARDS  OF  THE  AIR  ....      199 

XIX. — A  DANGEROUS  NEIGHBOR    .          .          .          .211 

XX. — THE  END  OF  THE  STORY       .         .         .         .216 

INDEX     .........     223 


ILLUSTRATIONS 

PAGE 

Fig.  i.     FORMS  OF  BACTERIA      .          .         .         .15 

"            2. — FLAGELLA  OF  BACTERIA          ...  17 

"            3. — SPORES  IN  BACTERIA      ....  20 

Plate        I. — TUBE  CULTURES  OF  BACTERIA         .          .  34 

"         II. — PLATE  CULTURES  IN  PETRI  DISHES          .  36 

"       III. — COLONIES  OF  BACTERIA           ...  38 

"        IV. — A    BACTERIAL    CULTURE    SHOWING    THE 

FORMATION  OF  GAS    ....  40 

Fig.          4. — STREPTOCOCCI  FROM  A  CULTURE      .          .  41 

"            5. — STAPHYLOCOCCUS  FROM  A  CULTURE           .  42 

"            6. — BACILLI  FROM  A  CULTURE       ...  42 

Plate       V. — NODULES  ON  CLOVER  ROOTS            .          .  56 

Fig.          7. — NODULE  BACTERIA         ....  58 

14            8. — STREPTOCOCCUS  PYOGENES     ...  72 

"            9.— STAPHYLOCOCCUS  PYOGENES  ...  73 

ix 


Illustrations 


PAGE 


Fig.         10. — TUBERCLE  BACILLI         ....  84 

Plate      VI. — TUBERCLES  IN  THE  LUNG         ...  86 

"      VII. — A  TUBERCLE  IN  THE  LUNGS  :  HEALED      .  88 

"    VIII. — TUBERCULOUS  CAVITIES  IN  LUNG    .          .  90 

IX. — CULTURES  OF  THE  TUBERCLE  BACILLUS  .  92 

X. — A  SNEEZE  PLATE  CULTURE     ...  94 

Fig.         ii. — THE  BACILLI  OF  TYPHOID  FEVER     .  101 

12. — THE  PNEUMOCOCCUS      .          .          .          .116 

13. — BACILLUS  DIPHTHERIA  .          .          .          .126 

14. — TETANUS  BACILLI           ....  128 

Plate     XI. — LEUCOCYTES  AND  PHAGOCYTES         .          .  146 

Fig-         15- — PHAGOCYTES  AND  VACCINES    .          .          .  167 

Plate   XII. — A  DIRTY  HUMAN  LUNG            .          .          .  202 

"    XIII. — TRACKS   OF   A     WANDERING     "TYPHOID 

FLY" 214 


The  Story  of  the  Bacteria 


THE  STORY  OF  THE  BACTERIA 


CHAPTER  I 

THE  CELLS  OF  THE  HUMAN  BODY — WHAT  THEY 
ARE,  AND  WHAT  THEY  DO 

BEFORE  beginning  to  study  those  low- 
liest and  smallest  forms  of  life,  the 
bacteria,  I  wish  to  ask  my  reader  to  look  with 
me  in  this  chapter  at  some  of  the  higher  and 
more  complex  forms  of  living  things.  In  do- 
ing this  we  shall  be  following  the  course  which 
scientific  research  has  taken,  and  from  the 
vantage-ground  thus  gained  we  shall  be  able 
the  more  easily  to  spell  out  the  simple  but 
significant  story  of  the  bacteria,  which  it  is 
the  purpose  of  this  little  book  to  tell. 

In  general  anatomy  we  learn  that  the  body 
consists  of  a  bony  framework,  around  which 


2  The  Story  of  the  Bacteria 

various  tissues  and  organs  are  securely  and 
compactly  grouped.  When  we  have  learned 
the  size,  shape,  number,  relations,  and  names 
of  all  these  parts,  our  study  of  macroscopic  or 
general  anatomy  is  done.  If,  however,  enter- 
ing that  department  of  science  known  as 
histology,  or  minute  anatomy,  we  trace  the 
manner  in  which  these  parts  are  made  beyond 
the  point  where  the  naked  eye  can  avail  us, 
we  find  that  they  are  all  composed  of  certain 
tiny  organisms  called  cells,  and  that  these 
cells  are  held  together  and  associated  by  cer- 
tain materials  which  lie  between  them. 

Just  as  the  chemist  has  his  atoms  and 
molecules,  to  which  in  the  last  analysis  he  re- 
fers the  properties  which  all  known  substances 
possess,  and  explains  by  differences  in  their 
nature  and  movements  the  various  chemi- 
cal phenomena  which  matter  exhibits,  so  we 
may  refer  both  the  structural  features  and  all 
the  activities  of  the  animal  body  back  to  the 
structure  and  activities  of  our  elements — the 
cells.  While  the  chemist,  however,  must  infer 
the  existence  of  his  atoms  from  their  deeds, 
armed  with  the  microscope  we  can  see  our 


The  Cells  of  the  Body  3 

cells,  observe  the  things  they  do,  and  definitely 
trace  out  their  life-history. 

Cells  are  little  masses  of  matter  of  peculiar 
chemical  constitution,  and  of  varied  shape  and 
consistence,  which  at  some  time  exhibit  that 
complex  of  phenomena  which  we  call  life:  and 
the  life  of  one  of  the  higher  animals  is  simply 
the  sum  of  the  more  or  less  independent  but 
co-ordinated  lives  of  the  cells  which  compose 
it,  all  acting  in  harmony. 

Living  things  differ  from  the  non-living  in 
that  they  have  certain  activities  through  which 
their  life  is  expressed.  In  the  first  place,  they 
are  capable,  in  spite  of  various  opposing  forces, 
of  maintaining  their  individuality,  and  by 
holding  a  balance  between  waste  on  the  one 
hand  and  assimilation  on  the  other,  a  series  of 
capacities  arises  which  we  call  nutrition, 
growth,  and  development.  Living  things,  in 
the  second  place,  possess  certain  activities  by 
means  of  which  they  are  capable  of  producing 
new  individuals  like  themselves — in  other 
words,  they  are  endowed  with  the  power  of 
reproduction.  Lastly,  living  bodies,  in  re- 
sponse to  varied  influences,  are  capable  of 


4  The  Story  of  the  Bacteria 

doing  certain  things  in  the  way  of  movements 
or  of  elaboration  of  peculiar  chemical  products, 
etc.,  and  these  are  called  their  functions. 

It  will  be  observed  that  in  enumerating 
these  activities  I  have  spoken  of  them  not  as 
characteristic  of  man,  or  of  any  special  animal 
or  plant,  but  of  living  things  in  general.  All 
life  finds  expression  in  these  ways.  The  means 
by  which  the  living  being  does  these  things 
may  be  in  one  case  exceedingly  primitive,  and 
in  another  very  complicated,  but  this  does  not 
alter  the  essential  character  of  the  ends  which 
it  achieves. 

If  you  tie  a  bit  of  muslin  over  a  water  faucet 
and  allow  the  water  to  trickle  slowly  through 
it  for  a  few  hours,  you  will  find  on  removing 
it  that  a  more  or  less  abundant  greenish  scum 
has  collected  on  the  cloth.  Wash  this  care- 
fully into  an  open  dish,  and  let  it  remain  for  a 
few  days  in  a  light  warm  place,  and  then 
examine  the  sediment  under  a  microscope, 
and  you  will  find  a  very  celebrated  creature. 
It  is  called  an  amoeba.  It  looks  like  a  little 
lump  of  transparent  or  slightly  granular  jelly. 
You  will  see  it  thrusting  out  portions  of  itself 


The  Cells  of  the  Body  5 

in  the  form  of  longer  or  shorter  arms,  and 
then  withdrawing  them  and  sending  out 
others  in  another  place,  apparently  in  the 
most  aimless  way;  or  you  may  see  it  rolling 
itself  over  and  over,  or,  if  I  may  so  say,  flow- 
ing along  so  that  it  travels  with  considerable 
speed.  Perhaps  some  microscopic  vegetable 
may  lie  in  its  way,  and  it  will  flow  over  and 
enclose  this,  and,  after  digesting -portions  of  it, 
expel  the  residue  from  whichever  side  or  sur- 
face of  its  body  may  be  most  convenient.  If, 
in  a  quiescent  condition,  it  be  touched  by  an 
external  object,  you  may  see  it  move  in  direct 
response  to  the  irritation.  If  you  are  fortu- 
nate in  your  observation,  you  may  see  a  con- 
striction appear  around  some  part  of  the  lump, 
which  grows  gradually  deeper  until  a  portion 
of  the  mass  separates  from  the  rest  and  crawls 
off  on  its  own  hook  as  a  new  and  independent 
amoeba.  It  has  no  lungs  and  yet  it  breathes; 
no  mouth,  still  eats;  no  definite  shape,  yet 
grows;  no  nerves,  yet  is  sensitive;  no  sex, 
yet  may  give  birth  to  endless  progeny. 

Now  this  amoeba  is  one  of  the  lowest  and 
simplest  of  creatures,  and  is  the  type  of  a 


6  The  Story  of  the  Bacteria 

cell — a  creature  which  is  composed  of  a  single 
cell — and  all  the  activities  which  I  have  men- 
tioned as  characteristic  of  living  things  are 
exhibited  in  it.  It  is  a  perfectly  independent 
being,  doing  everything  for  itself,  and  doing 
nothing  particularly  well,  except,  perhaps, 
performing  the  function  of  reproduction,  which 
it  does  with  such  ease  and  nonchalance 
as  leaves  little  to  be  desired.  The  young 
which  it  produces  are  just  like  the  parent, 
single  cells,  and  their  very  first  post-natal  act 
may  be  to  give  birth  to  other  amcebas. 

Now  let  us  advance  a  step  in  the  scale  of 
being,  to  an  animal  composed  of  several  cells. 
There  is  a  little  creature,  one  of  the  group  of 
sponges,  called  olynthus.  Let  us  start  with 
the  ovum  of  the  animal,  which  is  a  single  cell, 
not  very  unlike  the  amoeba  in  appearance. 
Under  suitable  conditions,  this  cell  divides  as 
the  amoeba  does,  and  two  cells  are  produced, 
just  exactly  alike.  They  do  not  separate, 
however,  as  do  the  amoebas,  to  become  inde- 
pendent individuals,  but  remain  fastened 
together;  then  each  cell  divides  again,  and 
these  still  further,  until  we  have  a  little  mass 


The  Cells  of  the  Body  7 

of  cells  all  looking  alike,  and  the  whole  some- 
what resembling  a  mulberry  in  shape.  But 
now  a  change  comes;  the  cells  on  the  outside 
become  longer  than  the  rest,  and  little  hair- 
like  processes,  called  cilia,  grow  out  from  them 
and  begin  to  vibrate  to  and  fro,  and,  acting 
like  tiny  oars,  propel  the  little  creature  through 
the  sea.  Presently  the  rest  of  the  cells  arrange 
themselves  so  as  to  form  a  central  cavity,  with 
an  opening  at  one  side,  the  whole  looking  like 
a  tiny  cup.  The  animal  now  attaches  itself  to 
a  sea-weed  or  a  rock,  and  no  longer  needing 
the  locomotive  cilia,  they  disappear;  but  as  it 
can  no  longer  travel,  it  can  no  longer  seek  its 
food,  which  must  be  brought  to  it.  Accordingly 
we  presently  find  that  through  the  sides  of  its 
body  little  holes  appear,  and  the  cells  lining 
the  central  cavity  lengthen  and  develop  cilia, 
whose  vibrations  maintain  a  current  of  water 
through  the  body,  which  brings  with  it  oxygen 
and  food.  This  is  the  adult  olynthus. 

Now  observe,  if  you  please,  what  has  hap- 
pened in  the  development  of  this  little  crea- 
ture. A  single  cell  divided  into  several  cells, 
at  first  all  just  alike,  and  all  doing  the  same 


8  The  Story  of  the  Bacteria 

thing.  But  soon,  as  if  in  response  to  the 
growing  needs  of  the  animal,  certain  of  the 
cells  developed  a  special  apparatus,  and  a 
special  capacity  for  performing  rapid  move- 
ments, and  this  capacity  was  associated  with 
changes  in  the  form  of  the  cells, — a  specializa- 
tion which  signalized  its  advance  to  a  higher 
type  of  existence. 

Just  here  we  come  upon  the  great  principle, 
in  a  very  simple  form,  upon  which  the  enor- 
mous differences  between  higher  and  lower 
animals  rest, — the  principle  of  the  physiologi- 
cal division  of  labor  in  cells.  The  more 
perfect  the  individual  is,  the  more  elaborate 
do  we  find  the  expression  of  this  principle. 

The  difference  between  the  amoeba  and  the 
olynthus  from  our  present  point  of  view — that 
which  makes  of  the  latter  a  higher  animal  than 
the  former — is  that  it  has  a  certain  group  of 
cells  set  apart  to  do  a  special  thing,  to  move 
rapidly;  amoeba  moves,  but  not  so  rapidly 
nor  with  such  directness.  If  another  group  of 
cells  were  set  apart  in  olynthus  to  do  the 
digesting,  no  new  cell  powers  would  be  devel- 
oped which  the  amoeba  does  not  possess;  the 


The  Cells  of  the  Body  9 

primitive  assimilating  power  would  simply  be 
specialized  and  intensified,  and  the  animal 
would  have  risen  to  a  higher  grade  of  being. 

It  would  not  be  difficult,  did  space  permit,  to 
trace  the  manner  in  which,  as  we  pass  upward 
in  the  animal  series,  certain  groups  of  cells  be- 
come more  and  more  elaborate  in  structure  as 
they  assume  higher  and  more  specialized  ca- 
pacities. We  cannot  tarry  for  this,  but  will 
glance  for  a  moment  at  the  exhibition  of  this 
principle  in  the  development  of  man.  In  man, 
too,  life  commences  in  a  single  cell  called  the 
ovum;  a  cell  which,  though  harboring  poten- 
tialities of  the  highest  order,  in  many  respects 
greatly  resembles  our  little  denizens  of  the 
water.  This  cell,  under  suitable  conditions, 
divides  and  subdivides,  forming  a  little  cluster 
of  cells  all  looking  alike.  Then  these  cells 
arrange  themselves  in  layers;  some  of  them 
assume  special  forms  as  they  increase  in  num- 
ber, and  develop  special  capacities,  and  group 
themselves  to  form  the  various  tissues  and 
organs  of  the  mature  body,  which  finally  is 
formed  of  a  grand  community  of  co-ordinated 
groups  of  cells,  some  of  which  have  acquired 


io          The  Story  of  the  Bacteria 

the  power  to  do  special  things  in  the  most 
perfect  way,  while  others  have  remained  in  a 
condition  of  comparatively  low  organization. 
Let  us  look  at  two  examples  of  these  two 
types  of  cells  from  the  adult  body — first  at 
certain  muscle  cells.  These  in  the  very  young 
animal  look  just  like  many  other  cells;  they 
are  individuals,  they  are  alive  and  their  life 
finds  expression,  just  as  the  amoeba's  does,  in 
certain  activities — nutrition,  growth,  function, 
and  reproduction.  Presently  they  become 
longer  than  their  neighbors,  little  striations 
appear  along  their  sides,  they  grow  long  and 
narrow  until  at  last  they  are  little  thread-like 
bodies  with  a  very  complicated  internal  struct- 
ure, and  are  grouped  in  bundles  to  form  the 
muscles  as  we  see  them  with  the  naked  eye. 
The  peculiarities  of  structure  of  these  muscle 
fibres  are  necessary  for  the  performance  of  the 
work  which  they  have  specially  to  do — namely, 
the  accomplishment  of  rapid  and  powerful 
movements.  Now  the  capacity  of  the  muscle 
cells  for  doing  this  work  has  been  acquired,  if 
I  may  say  so,  at  the  expense  of  some  of  the 
other  capacities  which  they  originally  possessed 


The  Cells  of  the  Body  n 

in  common  with  other  cells.  Thus  the  power 
of  reproduction  is  in  them  almost  if  not  quite 
completely  absent.  They  can  also  no  longer 
seek  out  and  take  up  crude  food,  but  it  has  to 
be  prepared  for  and  brought  to  them,  and  in 
order  that  this  may  be  done  certain  other  cells 
in  the  body  develop  the  power  of  elaborat- 
ing a  peculiar  fluid — gastric  juice,  which  helps 
to  change  the  crude  food  so  that  it  finally 
becomes  fitted  for  the  nourishment,  among 
others,  of  the  special  workers,  the  muscle 
cells;  other  cells — the  red  blood  cells — de- 
velop the  capacity  of  bringing  them  oxygen, 
and  in  doing  so  have  lost  many  capacities 
which  are  possessed  by  lower  forms.  Other 
cells  develop  in  a  peculiar  way  to  form  the 
nerves  by  which  all  the  various  parts  of  the 
body  are  brought  into  harmonious  action,  and 
so  on.  Thus  we  see  in  the  higher  animals 
each  highly  developed  cell  working  for  the 
others  as  well  as  for  itself  and  for  the  organ- 
ism as  a  whole,  only  its  chief  endeavor  is  con- 
centrated in  some  one  special  thing,  and  as  a 
result  of  this  concentration  some  of  the  more 
general  cell  powers  are  lost  or  diminished. 


12          The  Story  of  the  Bacteria 

Did  time  permit,  I  should  like  to  picture  for 
you  the  character  and  destiny  of  some  of  the 
lower  forms  of  cells,  which  we  find  in  the  hu- 
man body, — those  which  have  not  undergone 
that  differentiation  in  structure  and  function 
which  belongs  to  higher  types;  to  speak  of 
the  marvellous  potentialities  which  are  dor- 
mant in  them;  to  show  you  how  their  very 
simplicity  of  existence,  the  absence  of  special 
powers,  and  their  boundless  capacity  for  re- 
production particularly  fit  them  to  become  the 
conservators  of  the  individual;  to  indicate 
what  an  important  role  some  of  them  play 
in  the  healing  of  wounds  and  in  the  formation 
of  new  tissues.  So  we  are  not  to  think  of  the 
lower  forms  of  cells  in  the  body  as  insignifi- 
cant, because  under  ordinary  circumstances 
their  being  and  performances  are  humble 
and  inconspicuous,  for  they  seem  to  be  ever 
ready,  either  resting  quietly  in  their  tiny  nooks 
within  the  solid  tissues,  or  driven  restlessly  in 
the  rushing  torrent  of  the  blood,  to  assume 
again  the  lowly  but  active  powers  of  embry- 
onic cells,  and  begin  when  necessary  the  work 
of  reproduction  and  repair. 


The  Cells  of  the  Body  13 

These  cells  have,  too,  a  most  important  r61e, 
as  we  shall  see  by  and  by,  in  combating  the 
incursion  of  certain  forms  of  bacteria  which 
now  and  then  obtrude  themselves  into  this 
happy  family  of  cells  which  makes  up  the 
human  body. 

We  have  thus  seen  that  all  the  varied  struct- 
ures and  functions  of  the  human  body  are  but 
the  combined  expression  of  the  structure  and 
lives  of  the  cells  which  compose  it,  all  co-ordi- 
nated and  working  in  harmony  by  means  of  a 
self -built,  cellular  mechanism.  Starting  with 
the  type  of  the  most  simple  of  living  things, 
a  single  cell,  the  finished  organism  is  an 
aggregate  of  the  progeny  of  the  original  cell, 
some  groups  of  which  have  developed  special 
forms  and  powers,  in  accordance  with  a  uni- 
versal principle  in  nature.  So  the  doctrine  of 
evolution,  even  should  the  record  of  the  rocks 
be  incomplete  and  perfect  continuity  in  the 
grouping  of  living  species  fail,  still  finds 
epitomized  in  every  animal  and  plant  which 
has  escaped  from  the  primitive  simplicity  of 
the  lowest  forms,  a  most  pertinent  illustration 
and  convincing  proof. 


CHAPTER  II 

BACTERIA    AND    SOME    OF    THE    THINGS    WHICH 
THEY  DO 

THERE  are  many  very  good  reasons  for 
believing  that  when  life  first  appeared 
upon  the  earth  it  showed  itself  in  a  very  sim- 
ple and  primitive  form,  in  some  such  form 
perhaps  as  we  have  seen  in  the  amoeba  or 
other  simple  cells.  But  as  the  ages  passed,  in 
accordance  with  the  principles  of  the  physio- 
logical division  of  labor,  which  we  have  glanced 
at  in  the  last  chapter,  many  of  the  living 
beings  gradually  assumed  more  and  more 
complex  forms  and  capacities. 

Not  all  living  things,  however,  shared  in 
these  evolutionary  changes.  There  is,  in  fact, 
a  great  group  of  lowly  plants,  so  small  as  to 
be  quite  invisible  to  the  naked  eye,  and  which 
until  within  a  few  years  have  been  entirely 

14 


What  Bacteria  Do  15 

unknown  to  man,  which  still  linger  in  the 
primitive  simplicity  which  we  imagine  to  have 
belonged  to  the  earth's  earliest  denizens. 
These  are  the  bacteria. 

So  small  are  the  bacteria,  and  so  simple  in 
their  structure  and  activities,  that  it  has  not 
been  an  easy  task 
for  scientific  men 
to  decide  whether 
they  belonged 
among  animals  or 
plants.  It  is  now 
definitely  settled, 

J  FIG.    I. — FORMS   OF   BACTERIA 

however,  that  they 

are  plants,  and  are  closely  related  to  the  sea- 
weeds. 

Bacteria  vary  a  good  deal  in  shape,  but 
in  general  they  are  either  spheroidal  or  ovoidal, 
like  a  billiard-ball  or  an  egg;  or  rod-shaped, 
like  a  lead-pencil;  or  spiral-shaped,  like  a 
cork-screw.  Some  are  separate,  some  clus- 
tered. Fig.  i: 

They  are  in  general  so  very  small  that  we 
can  hardly  form  a  conception  of  them  except 
by  comparison  with  some  well-known  objects. 


16  The  Story  of  the  Bacteria 

One  of  the  most  common  of  the  bacteria  is  a 
little  rod,  so  small  that  if  you  were  to  put  fif- 
teen hundred  of  them  end  to  end,  the  line 
would  scarcely  reach  across  the  head  of  an 
ordinary  pin.  If  you  look  at  them  with  a 
magnifying  power  so  great  that,  if  it  could  be 
applied  to  him,  it  would  make  a  man  look 
about  four  times  as  tall  as  Mount  Washington, 
they  do  not  look  larger  than  this.  We  can 
see,  however,  that  they  are  made  up  of  a 
slightly  granular  material  surrounded  by  a 
somewhat  denser  envelope. 

The  bacteria  appear  under  the  microscope 
as  pale  translucent  bodies,  and  the  student 
usually  finds  it  necessary,  in  order  to  see  their 
outlines  clearly,  to  stain  them  with  some 
one  of  the  aniline  dyes — red,  or  blue,  or  violet, 
— when  they  become  very  distinct. 

When  they  are  alive  and  suspended  in  fluids 
many  of  the  rod-like  and  spiral  bacteria  can 
perform  the  most  elaborate  and  astonishing 
series  of  movements.  They  swim  slowly,  they 
turn  about,  they  roll  over,  they  wriggle,  dart 
forward,  retreat,  bang  against  one  another, 
rest  awhile,  sway  to  and  fro,  plunge  off  again, 


What  Bacteria  Do  17 

and  so  on  through  varying  phases  of  move- 
ment until  the  head  swims  and  the  eye  tires  in 
following  them.  This  move- 
ment, in  some  of  the  bac- 
teria at»  least,  is  induced  by 
a  little  hair-like  projection 
from  the  end  of  the  organ-  FIG.  2.  — FLAGELLA 

«  •    1  M  -11  OF  BACTERIA 

ism,  which  vibrates  rapidly 
to  and  fro — Fig.  2.  It  is  very  difficult  to 
see  these  little  projections  or  flagella,  even 
with  the  most  powerful  microscopes,  but, 
notwithstanding  this,  they  have  actually 
been  photographed,  and  in  some  cases 
the  image  of  the  flagella,  which  failed  to 
make  an  impression  on  the  retina,  has  been 
caught  and  fixed  by  the  sensitive  plate  in  the 
camera. 

Warmth,  moisture,  oxygen,  and  some  or- 
ganic matter  are  the  simple  conditions  re- 
quired for  the  activities  of  the  bacteria. 

When  the  conditions  are  favorable  they  may 
increase  in  number  to  a  degree  which  is  limited 
only  by  their  surroundings.  A  little  constric- 
tion appears  around  one  of  the  bacteria;  it 
grows  a  little  longer,  a  partition  forms  across 


i8          The  Story  of  the  Bacteria 

the  middle,  and  in  the  place  of  one  there  are 
two  full-fledged  bacteria.  These  may  at  once 
fall  apart  and  each  new  individual  go  on  di- 
viding as  before,  or  they  may  cling  together, 
forming  threads  or  chains  of  varying  length, 
or  clumps  or  masses. 

So  rapid  is  this  mode  of  reproduction  that 
a  single  germ  by  this  process  of  growth  and 
subdivision-  may  give  rise  to  more  than  sixteen 
and  a  half  millions  of  similar  organisms  within 
twenty-four  hours.  It  has  been  calculated  by 
an  eminent  biologist  that,  if  the  proper  condi- 
tions could  be  maintained,  a  little  rod-like 
bacterium,  which  would  measure  only  about  a 
thousandth  of  an  inch  in  length,  multiplying 
in  this  way,  would  in  less  than  five  days  make 
a  mass  which  would  completely  fill  as  much 
space  as  is  occupied  by  all  the  oceans  on  the 
earth's  surface,  supposing  them  to  have  an 
average  depth  of  one  mile. 

Let  not  the  timid  soul  tremble,  however,  for 
the  principle  of  the  survival  of  the  fittest  and 
the  influences  of  environment  have  kept  our 
prolific  organisms  so  well  in  check  that  the 
world  had  grown  very  old  and  its  favored 


What  Bacteria  Do  19 

nursling,  man,  pretty  well  along  in  experience 
and  skill  before  ever  he  recognized  the  exist- 
ence of  these  his  microscopic  contemporaries 
and  possible  ancestors. 

The  struggle  for  existence  goes  on,  where 
varying  forms  of  bacteria  are  growing,  as 
fiercely  as  ever  it  did  among  more  highly  or- 
ganized beings.  One  race  succeeds  another, 
one  species  adapts  itself  to  the  conditions 
which  brought  about  the  extinction  of  its 
predecessors.  Hardy  individuals  struggle  with 
their  weaker  neighbors  as  the  food  grows  scanty 
in  their  microscopic  seas,  and  the  weaker  goes 
to  the  wall. 

Many  forms  possess  the  power  of  living  and 
multiplying  in  the  manner  described  above  so 
long  as  the  proper  conditions  prevail,  but  when 
life,  owing  to  some  change  in  the  environment 
becomes  no  longer  possible,  the  vital  powers 
collect  themselves  in  a  little  shining  mass  in 
one  end  of  the  bacterium,  which  surrounds 
itself  by  a  dense  membrane,  and  in  this  form, 
which  is  called  a  spore, — Fig.  3, — it  can  survive 
adverse  conditions  which  in  the  ordinary  form 
would  have  destroyed  its  life.  Restore  it 


20          The  Story  of  the  Bacteria 

to  the  needed  conditions  and  the  spore  swells 
into  a  bacterium  again,  and  the  roots  of 
a  new  ancestral  tree  begin  to  sprout. 

These  bacteria  are  really  very  simple  forms 
of  cells,  and  like  the  cells 
which  we  have  looked  at  in 
the  last  chapter,  their  life 
expresses  itself  in  certain 
activities;  they  move,  they 
nourish  themselves  and 
grow,  they  reproduce  their 
kind.  They  have  the  power  in  carrying  on 
the  processes  of  their  own  nutrition,  when 
moisture  and  air  are  present,  of  tearing  to 
pieces,  in  the  chemical  sense,  dead  organic 
material,  using  up  such  parts  of  it  as  they  need 
for  their  own  purposes,  and  setting  free  the 
rest  in  such  form  as  to  be  available  for  the  use 
of  other  living  things. 

Everybody  knows  who  thinks  about  it,  that 
the  supply  of  such  material  as  makes  up  the 
bulk  of  the  tissues  of  man,  animals,  and  plants, 
on  this  earth,  is  limited.  So  that  if  things  were 
not  so  arranged  that  living  beings  should  have 
the  use  of  the  material  which  goes  to  make  up 


What  Bacteria  Do  21 

their  bodies  for  only  a  comparatively  short 
time,  the  supply  would  run  short  and  new 
beings  could  not  continue  to  appear. 

When  that  mysterious  group  of  activities 
which  we  call  life  ceases  to  be  manifested,  in 
animals  and  plants  alike,  if  moisture  and  oxy- 
gen and  sufficient  warmth  are  present,  that 
process  known  as  putrefaction  or  decay  begins, 
by  which  the  old  combinations  of  matter  are 
broken  up  and  the  material  set  free  for  the  use 
of  other  beings.  Now  just  here  enter  the 
bacteria.  It  is  they  who  tear  these  old  organic 
compounds  asunder,  using  a  little  of  them 
as  may  suit  their  own  needs,  and  turning 
over  the  rest  to  their  earth  neighbors,  who 
have  got  higher  up  the  scale  of  being,  but 
not  yet  so  far  as  not  to  need  absolutely  and 
hourly  oxygen,  hydrogen,  nitrogen,  and  carbon, 
to  keep  their  life's  furnaces  a-going. 

It  is  a  very  motley  group  of  chemical 
substances  which  these  bacteria  set  free  in 
feeding  themselves  on  nature's  waste  organic 
materials.  Sometimes  these  are  very  bad- 
smelling  gases,  sometimes  aromatic  substances, 
sometimes  they  are  sweet,  sometimes  they  are 


22          The  Story  of  the  Bacteria 

sour.  But  sooner  or  later  they  are  used  by 
some  animal  or  plant,  and  so  again  enter  the 
domain  of  life. 

Thus  ever  in  ceaseless  alternations  between 
life  and  death  these  elemental  combinations 
come  and  go.  And  ever  since  life  emerged 
from  its  primal  simple  forms  on  the  earth, 
the  bacteria  have  silently  gone  on  tearing 
the  worn-out  and  useless  to  pieces  and  turning 
it  over  in  new  combination  to  other  forms  of 
life. 

It  was  formerly  believed  that  such  lowly 
organisms  as  the  bacteria  could  spring  at  once 
into  being  wherever  in  nature  the  conditions 
were  favorable,  but  this  notion  of  spontaneous 
generation,  has  long  since  been  given  up,  be- 
cause it  was  shown  to  have  depended  upon 
insufficient  and  crude  observation.  We  now 
believe  that  every  living  thing  comes  from  some 
pre-existing  living  thing,  be  it  man,  beast, 
plant,  or  cell,  and  this  principle  holds  true  as 
well  among  the  bacteria  as  among  more  highly 
organized  beings. 

There  is  an  enormous  number  of  different 
species  of  bacteria,  each  one  of  which  appears  to 


What  Bacteria  Do  23 

preserve  its  individual  character  under  all  the 
varying  conditions  and  vicissitudes  to  which 
it  is  subject.  They  are  to  be  found  every- 
where in  nature.  Where  putrefaction  and  de- 
cay are  going  on  they  are  most  abundant,  but 
where  any  form  of  life  can  exist  they  are  pres- 
ent, either  dry  and  inactive,  or  where  moisture 
and  food  are  present,  growing  and  multiplying 
in  such  degree  as  their  surroundings  will  per- 
mit. In  all  natural  surface  waters,  in  the  soil, 
on  all  fruits,  vegetables,  and  plants;  in  the 
nose,  mouth,  digestive  canal,  and  excreta 
of  men  and  animals;  on  the  skin,  wherever 
dust  can  go  or  collect,  there  are  bacteria  of 
various  forms  in  greater  or  smaller  numbers. 
They  are  the  scavengers  in  the  economy  of 
nature. 

The  great  bacterial  laboratory  of  the  earth 
is  the  soil.  Here  the  most  wonderful  things 
happen  under  the  friendly  influence  of  these 
tiny  germs.  With  the  aid  of  other  lowly  liv- 
ing things,  they  help  in  the  gradual  erosion 
of  the  rocks,  from  which  the  mineral  ingre- 
dients of  the  soil  arise.  They  pull  the  tissues 
of  dead  trees  and  plants  and  animals  asunder, 


24          The  Story  of  the  Bacteria 

setting  free  moisture  and  gases,  and  working 
the  whole  stuff  over  into  the  vegetable  mould, 
from  which  the  farmer  wins  a  living  for  us  all. 
Sometimes  the  farmer  deliberately  sets  the 
bacteria  at  work,  through  the  silos  in  which  his 
crops  are  made  more  useful  for  the  food  of  cat- 
tle. He  keeps  them  busy  in  his  manure  heaps, 
which  they  "ripen"  for  the  special  needs  of 
the  soil.  He  uses  them  in  making  vinegar. 

One  of  the  most  important  of  the  chemical 
elements  in  the  growth  of  plants,  as  we  shall 
see  more  fully  later,  is  nitrogen.  In  the  water 
and  earth  certain  bacteria  manipulate  nitro- 
gen in  the  most  astonishing  fashion,  getting 
it  finally  into  proper  shape  for  the  uses  of  plant 
life. 

It  is  bacteria  which  make  milk  turn  sour. 
Other  forms  give  to  butter  and  to  cheese  their 
distinctive  flavors.  Some  of  them  help  the 
farmer  in  the  ways  which  we  have  spoken 
of  and  in  many  others.  But  there  are  bacteria 
which  play  him  false.  His  fruit  decays  when 
they  get  inside  through  bruises.  They  injure 
his  vegetables  when  they  find  a  chance.  His 
meat  and  milk  and  eggs  go  bad,  when  the 


What  Bacteria  Do  25 

wrong  sort  of  bacteria  get  at  them.  His  fence 
posts,  his  timber,  and  even  his  planted  seeds 
rot;  his  hay  heats  and  mildews;  his  water 
tanks  get  foul, — all  through  the  action  of 
bacterial  pests.  But  in  the  long  run  the 
beneficent  bacteria  win  out,  if  the  farmer 
bacteriologist  knows  what  to  do  and  when  to 
do  it,  and  stands  by  his  job. 

The  folks  who  tan  leather,  those  who  rot 
the  flax  plants  to  get  them  ready  for  the 
making  of  linen  thread,  and  the  people  who 
cure  the  tobacco  leaf  for  the  smoker's  delecta- 
tion, are  all  jugglers  on  a  large  scale  with 
capacities  and  whims  of  special  forms  of  living 
bacteria.  On  the  other  hand,  sugar  manu- 
facturers and  bakers  are  often  greatly  pestered 
by  the  presence  of  certain  bacteria,  which 
hamper  their  operations  or  damage  their  pro- 
ducts. The  canning  industries  are  engaged  in 
a  ceaseless  warfare  with  bacteria  which  some- 
times destroy  their  stuff  and  disgust  their 
customers. 

So  common  and  abundant  are  the  bacteria 
that  we  are  constantly  taking  enormous  num- 
bers of  them  into  our  systems  with  all  of  our 


26          The  Story  of  the  Bacteria 

uncooked  food.  We  should  not,  however, 
think  of  these  little  organisms  which  we  thus 
unwittingly  consume  as  things  necessarily  un- 
clean or  unwholesome.  For  they  are  only  little 
cells  after  all,  and  nearly  all  the  food  which  we 
consume,  whether  animal  or  vegetable,  is  made 
up  of  masses  of  cells  which  are  either  fit  to  eat 
in  their  natural  condition,  as  in  the  pulp  of 
fruits,  or  become  so  by  simple  cooking  or  other 
preparation. 

There  is  really  very  little  difference,  so  far  as 
wholesomeness  is  concerned,  between  the  few 
thousand  vegetable  cells  which  we  call  bacte- 
ria which  may  be  clinging  to  the  surface  of  a 
grape,  and  a  few  hundred  vegetable  cells  of 
larger  size  of  which  the  grape  itself  is  com- 
posed. Both  are  alike  worked  over  by  the 
digestive  organs,  under  ordinary  conditions, 
into  nutritive  material  for  the  uses  of  the 
body. 

There  are  poisonous  vegetables,  and  there 
are,  more  's  the  pity,  as  we  shall  see  by  and 
by,  poisonous  bacteria,  but  we  do  not  shudder 
as  we  swallow  a  mushroom  to  think  what 
might  have  happened  to  us  if  we  had  swallowed 


What  Bacteria  Do  27 

a  poisonous  toadstool  instead.  We  simply 
trust  to  the  gardener,  or,  if  he  be  dishonest 
or  ignorant,  see  to  it  ourselves  that  the  poison- 
ous are  not  liable  to  get  in  with  the  other 
plants,  and  then  go  on  enjoying  our  delicacies 
like  sensible  people. 

It  will  thus  be  seen  that  the  r61e  of  the 
bacteria  in  nature,  though  humble  and  silent, 
is  an  exceedingly  important  one.  They  are 
indispensable  to  the  continuance  of  the  higher 
forms  of  life  upon  the  earth.  They  may  well 
be  called,  in  general,  man's  invisible  friends; 
for  without  them  the  earth  would  soon  be 
depopulated  and  lapse  into  what  at  first  it 
was — a  lifeless  waste. 


CHAPTER  III 

HOW  THE  BACTERIA  ARE  STUDIED 

IF  you  take  a  small  wisp  of  hay,  put  it  in 
an  open  jar,  and,  covering  it  with  water, 
set  it  in  a  warm  place  for  a  day  or  two,  you 
will  presently  see  that  the  water  which  was  at 
first  perfectly  clear,  begins  to  get  turbid,  and, 
after  a  while,  a  grayish  scum  collects  on  the 
top.  Now  the  water  begins  to  give  off  a  dis- 
agreeable odor  of  decay.  This  is  what  has 
happened:  The  bacteria  of  various  forms, 
which,  in  the  dried  condition,  were  clinging  to 
the  hay,  or  which  were  in  the  water,  have  mul- 
tiplied to  such  an  extent  that  they  made  the 
water  turbid,  and  many  of  the  mobile  forms 
have  sought  the  surface,  where  the  oxygen 
was  most  abundant.  The  solution  of  or- 
ganic material  from  the  hay  has  furnished 

an   abundance  of  food,   and  as  the  bacteria 

28 


How  Bacteria  Are  Studied          29 

have  torn  this  into  simpler  forms  to  get  the 
particular  elements  which  they  needed  for 
their  own  use,  the  freed  material,  in  part  in 
the  form  of  bad-smelling  gases,  has  either 
been  set  free  into  the  air  or  remains  absorbed 
in  the  water. 

If  you  examine  a  tiny  droplet  of  the  water 
from  time  to  time  with  the  microscope,  you 
will  find  that  it  is  swarming  with  various  forms 
of  bacteria,  rods,  balls,  and  perhaps  spirals, 
many  of  them  in  active  motion.  But  you  will 
notice  that  from  day  to  day  the  prevailing 
forms  change.  One  day  the  little  rods  will  be 
most  abundant;  the  next,  these  may  have 
largely  disappeared,  and  perhaps  the  little 
balls  are  the  most  common  forms.  Then 
perhaps  a  new  set  of  rods  or  balls  will  appear 
of  a  different  size  from  the  first.  After  a 
while  you  will  find  that  the  bottom  of  the  jar 
has  become  covered  with  a  light-colored  sedi- 
ment, and  the  water  has  become  clearer. 

The  bacteria  of  one  form  or  another  have 
gone  on  dividing  and  subdividing,  breaking  up 
the  dissolved  organic  matter  in  the  water  until 
either  they  had  used  up  the  special  form  of 


30          The  Story  of  the  Bacteria 

material  which  was  best  suited  to  their  needs, 
or  until  the  material  which  they  had  set  free 
had  so  far  accumulated  as  to  prevent  their  fur- 
ther growth,  and  then  they  died,  self -poisoned, 
just  as  a  man  might  who  should  be  shut  up  in 
a  tight  room  until  the  accumulation  of  the 
products  of  his  respiration  and  excretion  had 
made  further  life  impossible.  Or  they  may 
die  because  other  species  of  bacteria  growing 
in  the  same  fluid  furnish  material  which 
poisons  their  neighbors.  So  the  proces- 
sion of  life  goes  on,  until  the  bottom  of 
the  jar  becomes  a  veritable  graveyard  of 
races. 

Some  forms  of  the  bacteria,  however,  which 
seem  dead,  and  fall  with  the  rest  to  the  bot- 
tom of  the  jar,  are  really  only  in  a  resting 
stage;  they  have  formed  spores  within  them- 
selves in  the  manner  described  above,  and  may 
lie  dormant  until  the  proper  conditions  come 
again,  when  they  may  spring  into  renewed 
activities.  But  new  species  may  from  time  to 
time  fall  into  the  jar  from  the  air  and  find  in 
the  water,  which  was  rank  poison  for  the  dead 
species  at  the  bottom,  just  the  food  they  need, 


How  Bacteria  Are  Studied         31 

and  so  will  the  drama  of  life  and  death  be 
enacted  anew  for  long  periods. 

In  such  a  confusing  mixture  as  this  the  stu- 
dent finds  it  no  easy  task  to  make  out  much 
except  differences  in  form  and  movement, 
in  the  jumble  of  tiny  plants.  What  he  needs 
to  do  is  to  get  each  species  by  itself,  so  that 
he  can  cultivate  it  alone,  and  find  out  what  it 
is  and  does  under  more  simple  conditions. 

For  this  purpose  it  is  best  to  use  some  solid 
substance  on  which  bacteria  will  grow. 

Boiled  potatoes,  which  have  been  carefully 
cleansed  and  sterilized — that  is,  free  from  any 
bacteria  from  the  soil  or  air — by  steaming,  will 
do  very  well  for  some  bacteria.  These  are 
cut  in  halves,  with  knives  sterilized  by  heat, 
being  held  in  the  fingers  which  have  been 
freed  from  living  germs  by  washing  with 
corrosive  sublimate,  and  placed  under  steril- 
ized bell- jars  or  in  tubes,  so  that  they  may 
not  be  contaminated  by  the  accidental  falling 
upon  them  of  bacteria  from  the  air.  Now,  by 
means  of  a  platinum  wire  set  in  a  glass  handle, 
which  has  been  sterilized  by  heating  to  red- 
ness, a  tiny  bit  of  the  bacteria-containing 


32          The  Story  of  the  Bacteria 

material  is  spread  upon  the  cut  surface  of  the 
potato,  and  the  latter  is  covered  again  and  set 
away  for  a  day  or  two  in  a  warm  place.  Usu- 
ally at  the  end  of  this  time,  if  all  goes  well, 
there  will  be  a  growth  of  the  bacteria  on  the 
potato  so  large  as  to  be  quite  visible  to  the 
naked  eye.  This  growth,  or  "  colony, "  as 
it  is  called,  which  is  made  up  of  myriads  of 
individual  bacteria,  the  offspring  of  those 
planted,  in  many  cases  presents  very  character- 
istic ways  of  growing  or  special  colors,  etc., 
characters  often  by  which  particular  species 
of  bacteria  may  be  distinguished  from  all 
others,  even  without  the  aid  of  the  microscope. 
This  gross  appearance  of  the  growing  colonies 
is  useful  in  the  recognition  of  species  which 
under  the  microscope  look  very  much  alike. 
Just  as  in  agriculture,  if  one  were  in  doubt 
as  to  two  specimens  of  seed  which  closely 
resembled  one  another — say  turnip  and  rape, 
for  example — by  sowing  them  in  the  ground 
and  observing  the  resulting  plants,  all  doubt 
would  be  removed. 

In  thus  planting  the  invisible  and  minute 
bacteria,  and  allowing  them  to  grow  until  such 


How  Bacteria  Are  Studied         33 

large  masses  of  colonies  are  formed  that  we 
can  readily  see  and  study  them  with  the  naked 
eye,  we  are  realizing  in  another  field  a  project 
which  was  urged  with  a  good  deal  of  persist- 
ency some  years  ago  for  finding  out  if  there 
were  inhabitants  in  the  moon,  and  for  com- 
municating with  them. 

It  was  proposed  to  build  in  outline  on  some 
great  plain  on  the  earth's  surface,  like  that  of 
Siberia,  a  gigantic  structure  so  large  that,  even 
assuming  that  the  lunar  inhabitants  had  no 
telescopes,  it  would  be  visible  to  them.  This 
structure  was  to  have  some  simple  suggestive 
mathematical  form  like  a  circle  or  triangle. 
Seeing  such  a  thing  appear  on  the  earth's  sur- 
face, it  was  thought  that  the  lunar  inhabitants 
would  probably  "catch  on"-— this  phrase  was 
not  known  in  those  primitive  times — and  erect 
a  similar  structure,  and  thus  communication 
would  be  established.  The  moon  project  fell 
through,  but,  as  we  have  seen  by  a  somewhat 
similar  device,  we  actually  make  the  inhabit- 
ants of  an  unseen  world  communicate  to  us 
to-day  some  of  the  secrets  of  their  hidden  life. 

But  the  knowledge  derived  from  the  mode 


34  The  Story  of  the  Bacteria 

of  growth  of  bacteria  on  potatoes  is  limited, 
because  as  the  potato  is  opaque  we  can  see 
only  the  surface  of  the  colony;  and,  further- 
more, not  all  the  bacteria  grow  well  on  pota- 
toes, and  some  do  not  grow  upon  them  at  all. 
So  the  next  step  is  to  make  some  transparent 
solid  substance  which  shall  be  a  suitable  soil 
for  bacterial  growth.  One  of  the  most  common 
and  useful  substances  for  this  end  is  a  10  per 
cent,  solution  of  gelatin  which  is  mixed  with 
beef  tea,  pepton,  and  a  little  common  salt, 
and  then  made  neutral  or  slightly  alkaline  by 
carbonate  of  soda.  This  mixture,  carefully 
heated  so  as  to  destroy  all  bacteria  which 
might  be  present  in  its  ingredients,  is  filled 
into  ordinary  glass  test-tubes  which  have  been 
sterilized  by  a  high  temperature.  These  are 
filled  about  one  third  full  of  the  gelatin  mixture, 
and  the  opening  is  stopped  by  a  plug  of  cotton 
batting.  Through  a  long  plug  of  cotton,  bac- 
teria cannot  pass ;  the  air  can  enter  and  leave 
the  tube,  but  all  bacteria  are  caught  by  the 
fibres  of  the  cotton.  After  the  gelatin  has 
become  cool  and  solid,  by  means  of  a  steril- 
ized platinum  wire,  some  of  the  bacteria  are 


PLATE  I. — TUBE  CULTURES  OF  BACTERIA 

The  two  tubes  at  the  left  contain  gelatin  culture  medium  and  show 
different  ways  of  growing  of  two  species.  The  tubes  at  the  right  show  a 
rough  surface  growth  on  a  white  egg  mixture.  Notice  the  cotton  plugs 
which  allow  the  air  to  enter  but  keep  out  all  contaminating  germs  from 
the  pure  cultures. 


of    THE 

UNIVERSITY 

OF 

ILIFQW 


How  Bacteria  Are  Studied         35 

introduced  into  the  gelatin,  the  cotton  plug 
being  removed  for  an  instant  for  this  purpose. 
Being  transparent,  the  gelatin  permits  us  to 
see  from  the  sides  as  well  as  from  the  surface 
the  exact  mode  of  growth  of  the  particular 
form  of  bacteria  introduced  into  the  tube, 
and  thus  we  learn  a  new  set  of  characteristics 
for  the  different  species  (see  Plate  I). 

But  if  we  need  to  keep  our  bacteria  at  a 
higher  temperature  than  that  of  an  ordinary 
room,  say  at  the  temperature  of  the  body,  at 
which  alone  some  forms  will  grow,  the  gelatin 
would  melt  and  the  bacteria  would  be  scat- 
tered through  it,  and  the  characteristic  mode 
of  growth  of  the  masses  or  colonies  would  be 
lost.  So,  for  this  purpose  we  use,  instead  of 
gelatin,  agar-agar,  a  material  derived  from 
a  sea-weed,  which  in  i  per  cent,  solution 
forms  a  gelatinous  solid  transparent  mass, 
which  may  be  heated  to  above  the  temper- 
ature of  the  body  without  fluidifying.  To 
this  are  added,  as  to  the  gelatin,  beef-tea, 
pepton,  etc. 

By  the  use  of  these  various  soils,  or  "culture 
media,"  as  they  are  called,  and  many  others 


36          The  Story  of  the  Bacteria 

such  as  beef -tea,  milk,  blood-serum,  etc.,  we 
can  arrive  at  a  series  of  characteristics  in 
the  mode  of  growth  of  various  bacteria  by 
which,  together  with  their  form  when  seen 
under  the  microscope,  we  can  distinguish 
them  one  from  the  other,  just  as  the  naturalist 
distinguishes  from  each  other  nearly  related 
animals  and  plants. 

!  It  is  obviously  of  the  greatest  importance, 
as  we  have  seen  above,  that  we  should  be  able 
to  separate  different  species  of  bacteria  from 
one  another  in  the  living  condition,  so  that  we 
may  have  growths  or  colonies  which  shall  con- 
tain one  species  alone  without  admixture  with 
any  other.  These  are  called  "pure  cultures.'* 
This  is  by  no  means  an  easy  task,  as  will  be 
appreciated  when  we  consider  how  exceedingly 
minute  the  organisms  are,  and  how  much  dan- 
ger there  is  that  the  bacteria  floating  every- 
where invisibly  in  the  air  may  become  mixed 
with  those  forms  which  we  are  studying.  By 
a  very  simple  device  elaborated  by  Dr.  Koch, 
of  Berlin,  we  are,  nevertheless,  able  at  any 
time  to  separate  one  species  from  another  with 
the  utmost  certainty,  or  from  a  mixture  of 


PLATE    II. — PLATE    CULTURES    IN    PETRI    DISHES 

The  upper  dish  contains  a  few  colonies,  the  lower  shows 
many,  of  various  sizes. 


How  Bacteria  are  Studied          37 

many  species  to  get  into  separate  tubes  pure 
cultures  of  each  species  by  itself.  This  is 
accomplished  by  what  is  called  the  "plate 
culture,"  the  details  of  which  are  as  follows: 
Suppose  we  have  a  mixture,  say  a  sample  of 
impure  drinking  water,  which  contains  four 
different  species  of  bacteria,  which  we  wish 
to  get  into  pure  cultures  in  separate  tubes. 

We  mix  a  small  amount  of  the  bacteria- 
containing  water  with  a  much  larger  amount  of 
the  above-described  nutrient  gelatin,  melted 
by  heat.  Then  we  pour  this  mixture  into  a 
shallow  glass  dish  with  a  glass  cover,  called  a 
Petri  dish,  which  has  been  carefully  sterilized 
by  heat,  so  as  to  form  a  thin  layer.  This 
soon  cools  and  becomes  solid.  The  Petri 
dish  is  covered  to  keep  out  any  bacteria  which 
may  be  floating  in  the  air,  and  to  prevent  its 
drying,  and  is  set  away  at  the  temperature 
of  the  living-room.  The  individual  bacteria 
which  were  scattered  through  the  gelatin  layer 
will  presently  commence  to  grow. 

After  a  few  hours  or  days,  as  the  case  may 
be,  if  we  look  at  the  gelatin-film  (see  Plate  III) 
we  see,  sometimes  with  the  naked  eye,  some- 


38          The  Story  of  the  Bacteria 

times  only  under  the  microscope,  little  points 
or  masses  scattered  through  the  gelatin,  which 
are  colonies  of  bacteria,  each  one  consisting 
of  hundreds  or  thousands  of  the  organisms 
which  have  grown  from  the  single  organism 
which  was  fixed  at  that  point  as  by  a  solid 
wall  when  the  gelatin  cooled. 

Of  course,  it  sometimes  happens  that  two  or 
more  of  the  original  germs  either  of  the  same 
or  different  species  were  solidified  in  the  gela- 
tin when  it  cooled  at  the  same  place,  and  then 
the  resulting  colony  will  consist  of  all  the 
organisms  which  have  grown  at  this  point, 
mixed  together  or  growing  closely  side  by 
side.  In  most  cases,  however,  the  little  colo- 
nies are  composed  of  the  descendants  of  a 
single  germ,  and  if  we  put  the  gelatin  plate 
under  the  microscope  we  can  see  the  different 
forms  of  the  colonies  which  have  grown  from 
the  different  species.  The  differences  in  the 
mode  of  growth  of  the  bacteria  when  planted 
and  studied  in  this  way  are  manifold:  some 
are  colored,  red,  green,  yellow,  orange,  violet, 
brown,  etc.;  some  are  colorless,  some  have 
sharply  defined  smooth  edges,  some  are  jagged 


PLATE    III. — COLONIES    OF    BACTERIA 

The  larger  of  these  colonies  growing  on  gelatin  in  a  Petri 
dish  show  fringed  borders  which  are  characteristic  of  the  species. 


How  Bacteria  are  Studied          39 

or  fringed — see  Plate  III ;  some  are  beaded,  or 
send  out  little  spines;  some  cause  the  gelatin 
in  their  immediate  vicinity  to  liquefy,  so  that 
they  come  to  lie  in  a  little  pool  of  fluid  in  a  pit 
or  depression  in  the  solid  gelatin. 

Now,  by  examining  the  plate  microscopically 
we  can  not  only  see  how  many  different  forms 
of  colonies  there  are — and  each  different  form 
of  colony  indicates  a  difference  in  the  spe- 
cies of  bacteria  composing  it, — but  nothing  is 
simpler  than,  directly  under  the  microscope,  to 
take  out  on  the  tip  of  a  sterilized  .platinum 
wire  little  bits  from  each  one  of  the  different 
forms  of  colonies,  and  transfer  them  to  sepa- 
rate tubes  of  gelatin.  Thus  we  secure  "pure 
cultures"  of  all  the  different  forms  of  bacteria 
which  were  contained  in  the  original  mixture. 
Thus,  minute  as  the  individual  bacteria  are,  ly- 
ing far  below  the  power  of  unaided  vision,  we 
are  able  to  manipulate  them  with  as  much  cer- 
tainty as  the  agriculturist  does  his  larger  plants. 

When  we  have  thus  got  different  species  of 
bacteria  separated  from  one  another  in  the 
form  of  pure  cultures,  we  can  experiment  on 
them  in  many  ways,  and  learn  their  varying 


40          The  Story  of  the  Bacteria 

characteristics.  We  can  plant  them  under 
such  conditions  that  their  oxygen  supply  is 
limited,  and  learn  whether  they  do  or  do  not 
thrive;  we  can  see  whether  they  grow  best  at 
high  or  low  temperatures,  whether  they  form 
gas  or  not,  and  what  degrees  of  heat  or  cold 
will  kill  them.  We  can  grow  them  in  large 
quantities,  and  study  the  chemical  compounds 
which  result  from  their  life  processes.  We  can 
apply  to  them  various  chemical  substances 
which  are  called  germicides,  or  disinfectants, 
and  find  out  to  which  of  these  and  in  what 
strength  they  most  readily  succumb. 

In  this  way  a  large  number  of  different 
species  of  bacteria  have  been  studied,  and 
these  have  been  arranged  in  groups  which 
have  some  characters  in  common.  So  that 
already,  although  the  study  of  the  bacteria  by 
the  new  methods  is  of  recent  date,  we  have  the 
outline  of  analysis  tables,  something  like  those 
made  for  the  identification  of  the  higher 
plants  in  Gray's  Botany,  for  instance,  by 
the  use  of  which  the  student  can  identify 
certain  of  the  better  known  forms  which  he 
may  come  across  in  his  studies. 


PLATE    IV. — A    BACTERIAL    CULTURE    SHOWING    THE 
FORMATION    OF    GAS 


The  cut  shows  the  lower  end  of  a  tube  of  gelatin  into 
which  a  needle  was  thrust  on  the  tip  of  which  were  a  few  gas- 
forming  bacteria.  As  these  have  grown  along  the  puncture 
gas  bubbles  have  collected. 


How  Bacteria  are  Studied          41 

The  nomenclature  in  bacteriology  is  still  in 
a  rather  chaotic  condition,  but  a  beginning  has 
been  made.     The  term  bacteria  (singular,  bac- 
terium) applies  to  the  whole  class  of  organisms 
of  whatever  shape.     They  are  also  sometimes 
called  " germs,"  or  ' 'mi- 
crobes," or  "micro-organ- 
isms," which  means  small 
living  beings.    The  round 
or     spheroidal     form    is 
called    ' l  coccus, ' '     which 
means  a  berry;  the  plural 
is  cocci.     The  botanical      FIG.4._STREPTOCOCCI 
name  of  the  most  com-         FROM  A  CULTURE 
mon   form  of  the  round 
or  spheroidal  bacteria  is  Micrococcus — that 
means    "a   little  berry."      Thus  there  is  a 
species  of  micrococcus  which  produces  a  yel- 
low color  when  it  is  growing  in  masses.     This 
species  is  called  Micrococcus  luteus — the  yel- 
low micrococcus. 

Another  genus  among  the  spheroidal  bac- 
teria is  called  Streptococcus — "a  chain  of  ber- 
ries"— Fig.  4 — because  the  little  balls  tend  to 
cling  together  and  form  longer  and  shorter 


42  The  Story  of  the  Bacteria 


tA 


chains  as  they  grow.  Another,  growing  in 
masses,  is  called  Staphylococcus — "a  bunch 
of  berries" — Fig.  5.  Then 
among  the  rod -shaped  bac- 
teria the  most  common  genus 
is  called  Bacillus  (plural, 
bacilli),  and  some  of  the 
FIG.  5.— STAPHYLO-  Species  of  this  genus  are 

COCCUS  FROM  A 

CULTURE  among  the  most  common  and 

abundant  forms — Fig.  6. 
Thus  with  a  temporary  and  provisional  sys- 
tem of  classification,   the  work  of  studying 
and  describing  the  bacteria 
is  steadily  going  on.     And 
if  to  see  and  describe  living 
beings  on  which  no  human 
eye  has  ever  rested  before 
be  satisfying,  it  will  be  long 
before  the  sighs  of  bacteri- 

1         •        -I       A    1  -,  FIG.      6. — BACILLI 

ological  A I  e  x  a  n  d  e  r  s  are       FROM  A  CULTURE 
heard  in  this  unseen  world, 
whose  very  shores  have  been  barely  touched 
by  the  new  explorers. 


CHAPTER  IV 

SOME   BACTERIAL  CURIOSITIES 

MOST  travellers,  and  some  people  who 
stay  at  home,  too,  have  now  and  then 
been  mystified  and  delighted,  when  not 
frightened,  to  see  in  the  night-time  that 
wavering,  cold,  uncanny,  but  beautiful  light, 
sometimes  tinged  with  the  most  exquisite 
green  or  blue,  which  is  commonly  called  phos- 
phorescence. Sometimes  it  is  seen  in  decay- 
ing plants  or  wood;  sometimes  bays  or  inlets 
of  the  sea  are  fairly  luminous  with  it.  The 
surface  of  dead  fish  and  of  meat  and  various 
kinds  of  vegetables  often  becomes  so  bright 
as  to  illuminate  the  storage  rooms  in  which 
they  lie. 

Some  time  since  there  was  brought  to  the 
laboratory  for  examination  a  cluster  of  sau- 
sages which  had  been  destined  to  grace  a 

43 


44  The  Story  of  the  Bacteria 

boarding-house  breakfast- table.  To  the  con- 
sternation of  the  maid  who  went  into  the  dark 
cellar  for  them  in  the  early  morning,  there 
hung  in  the  place  of  the  sausages  a  fiery 
effigy  which  seemed  to  her  more  like  the 
quondam  spirits  of  their  mysterious  ingredi- 
ents than  the  unctuous  homely  friend  of  the 
homeless  boarder. 

The  explanation  of  this  is  now  simple 
enough  without  recourse  to  the  supernatural; 
for  it  has  been  recently  shown  that  this 
curious  light  which  various  organic  sub- 
stances emit  is  due,  in  many  cases  at  least, 
to  the  enormous  numbers  of  certain  kinds  of 
bacteria  which  are  present  on  their  surfaces, 
hard  at  work  feeding  on  the  organic  com- 
pounds which  are  present  and  undergoing 
decay.  Pure  cultures  of  these  singular  bac- 
teria have  been  made  and  cultivated  in  con- 
siderable quantities.  These  bacterial  masses, 
together  with  the  tubes  in  which  they  were 
growing,  have  been  placed  in  a  dark  room 
with  an  open  watch  beside  them,  and  bacterial 
masses,  tubes,  and  all  actually  photographed 
by  their  own  light,  the  pointers  of  the  watch 


Some  Bacterial  Curiosities          45 

showing  distinctly  the  time  of  day.  So  it 
would  seem  that  this  cousin  of  the  will-o'- 
the-wisp — no  doubt  often  mistaken  for  him — 
is  no  malevolent  genius  after  all,  but  a  quiet 
little  citizen  working  away  as  diligently  as 
he  can  to  make  the  world  more  comfortable 
for  his  betters. 

It  has  long  been  known  by  the  makers  of 
beverages  that  alcohol  is  formed  in  certain 
sugary  mixtures  by  a  process  called  fermen- 
tation, and  that  this  tearing  to  pieces  of  the 
sugar  into  other  compounds,  one  of  which  is 
alcohol,  is  accomplished  by  a  little  living 
organism  called  yeast,  closely  related  to  the 
bacteria.  In  the  earlier  days  of  beer-  and 
wine-making  it  was  often  found  that  the  beer 
did  not  work  or  ferment  properly,  and  that 
wine  would  get  sour  or  bitter.  We  now  know 
that  these  irregularities  are  due  to  the  fact 
that  certain  kinds  of  bacteria  are  apt  to  get 
into  the  wine  or  beer  during  the  manufacture, 
and  when  they  do  a  bitter  struggle  for  food 
goes  on  between  the  yeasts  and  the  bacteria; 
or  the  latter  may  bide  their  time,  and  later 
in  the  process  begin  to  grow  and  produce 


46  The  Story  of  the  Bacteria 

very  undesirable  compounds  in  the  fluids. 
So  the  manufacturer  has  to  be  on  the  alert, 
and  at  the  right  moment  come  to  the  rescue 
of  his  army  of  servitors,  the  yeast  plants, 
and  introduce  into  his  beer  some  chemical 
substance  which  is  innocuous  to  them  but 
deadly  to  the  intruding  bacteria.  Or  he  may 
raise  his  wine  at  a  certain  period  to  such  a 
temperature  as  will  suffice  to  kill  the  bacteria 
but  not  injure  the  flavor  of  the  already  fer- 
mented juice.  Here  again  as  in  the  case  of 
the  farmer  we  see  the  bacteria  coming  into 
conflict  with  the  purposes  of  their  earth- 
neighbor — man . 

Some  of  the  bacteria  are  great  lovers  of 
oxygen,  and  if  they  are  shut  up  in  a  little  cell 
containing  a  few  drops  of  water  in  which  a 
bubble  of  air  has  been  enclosed,  after  a  while 
it  will  be  found  that  those  forms  which  are 
capable  of  locomotion  have  made  their  way 
from  all  parts  of  the  fluid,  which  is  a  veritable 
ocean  to  them,  and  are  closely  clustered 
around  the  air  bubble,  jostling  and  bumping 
against  one  another  in  the  most  reckless  way. 
It  seems  almost  as  if  this  rush  towards  the 


Some  Bacterial  Curiosities          47 

oxygen  were  an  evidence  of  volition  in  its 
simplest  form  way  down  on  the  lowest 
border-line  of  life. 

Some  forms  of  bacteria  are  exceedingly  in- 
vulnerable to  the  action  of  cold,  and  can  not 
only  move  actively  about  in  very  cold  water, 
but  can  remain  alive  for  long  periods  fast 
frozen  in  a  mass  of  ice.  Now  a  very  curious 
thing  has  been  noticed  in  the  ice  which  is 
gathered  in  these  regions  and  which  we  use 
for  domestic  purposes,  and  that  is,  that  the 
so-called  bubbly  streaks  which  we  usually 
see  in  our  ice  blocks  contain,  as  a  rule,  many 
more  bacteria  than  does  the  transparent  ice 
close  by. 

It  has  been  found,  on  cultivating  the  bac- 
teria from  the  bubbly  streaks,  that  the  species 
which  was  most  abundant  here  is  an  oxygen 
lover,  and  is  also  very  mobile.  Now  the 
bubbles  which  collect  in  streaks  or  layers  in 
the  ice  collect  during  the  daytime,  or  when 
the  ice  is  not  freezing  very  fast  below,  and 
there  is  time  for  the  air-seeking  bacteria  to 
gather  around  them  in  great  numbers.  But 
now,  when  a  clear  night  or  a  cold  snap  comes 


48          The  Story  of  the  Bacteria 

on,  the  ice  closes  around  both  bubbles  and 
bacteria,  and  we  have  formed,  to  use  the 
language  of  the  geologist,  an  air  and  fossil- 
bearing  stratum.  Only  our  bacterial  fossils 
are  not  dead,  and  all  we  have  to  do  in  order 
to  find  out  what  forms  of  life  were  present 
in  our  successive  geological  periods,  limited  per- 
haps only  by  a  night,  is  to  melt  a  bit  of  the  ice, 
mix  it  with  our  culture  gelatin,  and  in  a  day 
or  two  we  shall  have  a  whole  garden  of  grow- 
ing plants,  which  we  can  study  at  our  leisure. 

But  many  bacteria  can  survive  a  tempera- 
ture much  below  freezing.  Experiments  with 
liquid  air,  which  affords  extreme  degrees  of 
cold,  have  shown  that  exposure  to  more  than 
190°  C.  below  zero  leaves  some  bacteria  quite 
unharmed.  While  many  bacteria  thus  sur- 
vive extreme  cold,  they  do  not  multiply  at 
low  temperatures,  so  that  the  use  of  ice  in 
preserving  foods  is  of  great  importance. 

On  the  other  hand,  there  are  bacterial 
species  which  prefer  high  temperatures.  Thus 
some  forms  flourish  in  the  water  of  hot  springs 
at  a  temperature  of  170°  Fahrenheit.  These 
are  called  thermophylic  or  "heat  lovers." 


Some  Bacterial  Curiosities          49 

As  a  rule,  bacteria  are  soon  killed  by  bright 
sunlight,  and  even  in  diffuse  daylight  many 
pine  and  die. 

Among  the  most  curious  things  which  the 
bacteriologist  has  to  exhibit  in  his  bacterial 
conservatory  is  the  color-forming  species.  It 
is  only  when  they  are  growing  in  masses,  of 
course,  that  enough  color  is  formed  to  be 
visible;  but  then  one  may  see  in  the  little 
slimy  masses  which  cover  the  surface  of  the 
food  or  culture  media  in  the  tubes,  every 
color  of  the  rainbow  and  many  variations 
in  hue.  Sometimes  not  only  is  the  bacterial 
mass  itself  brilliantly  colored,  but  some  of 
the  chemical  substances  which  they  form  as 
they  grow  permeate  the  gelatin  and  give  it 
a  beautiful  fluorescence,  green  or  red. 

The  writer  was  not  long  ago  standing  be- 
side a  supper-table,  whose  sole  floral  decora- 
tion was  a  bunch  of  large,  exquisitely  tinted 
chrysanthemums,  when  a  friend  remarked 
upon  the  patience  and  skill  which  had  been 
required  to  develop  this  magnificent  flower 
by  artificial  selection  from  its  simple  and 
homely  ancestor,  and  queried  in  a  quizzing 


50          The  Story  of  the  Bacteria 

way  how  long  it  would  be  before  somebody 
would  be  trying  to  modify  the  colors  of  some 
of  the  bacteria  by  the  well-known  horti- 
cultural methods.  His  idea  was  a  clever  one, 
but  he  was  behind  the  times,  for  already  a 
German  bacteriologist  had,  starting  with  a 
deep  purple-forming  species  of  bacteria,  and 
selecting  and  replanting  the  lighter-colored 
colonies,  at  last  obtained  cultures  which  were 
nearly  white,  but  were  in  other  respects 
essentially  the  same. 

In  many  other  ways  the  bacteriologist  can 
modify  the  life  processes  of  bacteria  by  suc- 
cessive generations  of  selective  cultures.  Acid 
producers  can  be  restrained,  or  their  powers 
exalted.  Lovers  of  oxygen  can  be  made  to 
go  without  it.  The  fermentative  and  putre- 
factive capacities  of  many  forms  can  be 
profoundly  altered.  They  can  be  adapted 
to  strange  foods  and  to  outlandish  con- 
ditions. Harmful  species  can  be  rendered 
harmless  and  the  virulence  of  other  forms 
exalted. 

Thus  the  great  and  far-reaching  prin- 
ciples of  natural  selection,  in  accordance  with 


Some  Bacterial  Curiosities          51 

which  life,  slowly  emerging  from  its  primeval 
simplicity,  at  last  came  to  be  manifested  in 
that  grand  scale  of  living  beings  at  the  top 
of  which  man  stands  supreme,  are  still  to  be 
traced  way  down  among  the  invisible  or- 
ganisms which  typify  the  earliest  and  sim- 
plest expression  of  life. 

But  certain  of  these  color-forming  bacteria 
are  sometimes  very  disagreeable  intruders 
upon  domestic  life.  Occasionally,  without 
warning,  the  milk  of  a  particular  dairy 
suddenly  develops  a  very  uncanny  deep-blue 
color,  which,  like  an  epidemic,  spreads  to  all 
the  milk  which  is  stored  in  special  rooms. 
This  occurrence,  for  a  long  time  a  disagreeable 
and  costly  mystery,  is  now  known  to  be  due 
to  a  tiny  bacterium  of  the  genus  Bacillus? 
which,  floating  about  in  the  air  with  the 
dust,  from  time  to  time  infects  rooms,  and, 
falling  into  the  milk,  grows  there,  producing 
the  blue  coloring  matter. 

Sometimes  milk  gets  red  instead  of  blue, 
and  then  the  change  is  due  to  another  form 
of  bacteria  floating  with  the  dust.  Bread, 
too,  may  become  infected  in  the  same  way, 


52          The  Story  of  the  Bacteria 

and  the  dough  set  aside  in  bake-shops  over- 
night to  rise  has  not  infrequently  been  found 
in  the  morning  resplendent  with  colors  which 
fairly  rivalled  those  of  the  rising  sun. 

There  is  a  species  of  bacteria  in  every  good 
collection,  and  a  veritable  Nestor  among  the 
forms  known  to  man,  which  has  a  curious 
ecclesiastical  history.  Among  all  the  in- 
numerable natural  phenomena  which,  by  their 
striking  character,  infrequent  occurrence,  and 
lack  of  apparent  cause,  were  in  early  times 
relegated  to  the  domain  of  the  supernatural, 
none  perhaps  was  more  strange  and  uncanny 
than  the  sudden  appearance  on  the  moist 
surfaces  of  articles  of  food  of  little  bright-red 
shiny  droplets,  which,  gradually  spreading, 
at  length  formed  large  shiny,  deep,  rich-red 
masses,  looking  very  like  drops,  or  masses, 
or  clots  of  blood.  The  story  is  long  and 
tragic  of  the  dire  calamities,  unmentionable 
crimes,  and  swift  retributions  which  these 
strange  appearances  of  blood  were  supposed 
to  foreshadow. 

This  miracle  of  the  bleeding  Host  has 
appeared  again  and  again  in  the  hands  of  the 


CHAPTER  V 

AGRICULTURAL  CONJURERS 

LIVING  bodies  are  made  up  largely  of 
oxygen,  hydrogen,  carbon,  and  nitrogen. 
While  these  are  all  very  abundant  in  the 
world,  nitrogen  seems  to  be  about  the  most 
difficult  for  both  animals  and  the  higher  plants 
to  get  hold  of,  because  in  the  ordinary  form 
in  which  it  exists  in  the  atmosphere  it  is  not 
directly  available.  Man  and  his  relatives, 
the  meat-eating  animals,  get  nitrogen  mostly 
from  other  animals  or  from  plants,  and  ul- 
timately the  nitrogen,  which  animals  require, 
comes  from  plants.  The  higher  plants  get 
their  nitrogen  largely  from  certain  chemical 
compounds  in  the  soil  called  nitrates,  which 
the  bacteria  have  been  active  in  forming 
out  of  the  dead  stuff  of  former  living  things. 
Give  the  farmer  soil,  water,  air,  sunshine, 

55 


56          The  Story  of  the  Bacteria 

and  seed,  and  his  task  is  to  get  a  crop.  This 
seems  simple  enough.  In  fact  he  has  oxygen, 
hydrogen,  and  carbon  a  plenty.  The  trouble 
is  with  the  nitrogen,  which  is  so  abundant 
that  it  makes  up  about  four  fifths  of  the  vol- 
ume of  the  air.  But  plants  can't  eat  pure 
nitrogen.  So  the  farmer  has  to  secure  it 
in  a  roundabout  way.  As  all  animal  and 
vegetable  substances  contain  nitrogen,  and, 
when  dead  and  decaying  under  the  in- 
fluence of  bacteria,  give  up  those  nitrogen 
compounds  which  living  and  growing  plants 
require,  he  gets  this  dead  stuff  wherever  he 
can.  His  great  domestic  supply  is  from  his 
barnyard  manure.  This  is  in  truth  the  most 
valuable  product  of  his  farm,  if  he  knows  how 
to  care  for  and  use  it.  But  he  often  spends 
a  great  deal  of  money  in  buying  imported 
nitrogen  in  the  form  of  Chile  saltpetre  or 
other  compounds.  There  are  commercial 
laboratories  which  prepare  artificial  nitrogen 
compounds  for  the  farmer.  But  for  all  these 
things  he  has  to  pay  out  his  hard-earned  cash. 
Some  crops,  notably  grain,  take  a  great 
deal  of  nitrogen  out  of  the  soil,  so  that  if  a 


PLATE    V. — NODULES    ON    CLOVER    ROOTS 


Agricultural  Conjurers  57 

new  supply  be  not  furnished,  after  a  while 
the  land  becomes  impoverished.  This  is 
one  reason  why  there  are  in  some  parts  of 
the  country  so  many  abandoned  farms — toe 
little  nitrogen — and  the  atmosphere  full  of  it. 

It  has  long  been  clear  that  if  the  farmer 
could  only  directly  tap  the  atmospheric 
nitrogen,  his  fortune  would  be  made.  It 
has  been  known  ever  since  the  times  of  the 
old  Romans  that  what  is  called  "  green 
manuring,"  that  is  the  ploughing  under  of 
crops  of  leguminous  plants,  such  as  clover, 
enriches  the  soil  in  quite  a  remarkable  though 
mysterious  way.  But  the  reason  for  this 
common  practice  was  left  for  the  modern 
bacteriologist  to  discover.  And  here  enters 
one  of  the  most  noteworthy  of  the  bacterial 
conjurers. 

Farmers  and  other  students  of  plants  for 
a  long  time  have  been  familiar  with  certain 
little  nodules  or  tubercles  (Plate  V.)  growing 
on  the  roots  of  leguminous  plants  such  as 
clover,  peas,  beans,  etc.,  and  had  supposed 
that  they  indicated  some  kind  of  disease  of 
the  plant.  But  a  few  years  ago  it  was  dis- 


58  The  Story  of  the  Bacteria 


covered  that  these  root  nodules  are  made  up 
largely  of  rod-like  and  irregular-shaped  bac- 
teria (Fig.  7).  Several  forms  of  these  can 
now  be  cultivated  artificially,  and  it  has  been 
found  that  they  have  the  power  of  seizing 
upon  atmospheric  nitrogen  and  working  it 

over  into  available  form 
for  the  uses  of  their 
host.  These  bacteria 
get  into  the  rootlets 
of  the  leguminous  plant 
and  grow  there  as  par- 
asites, not  at  first  al- 
together welcomed  it 
would  seem.  But  pres- 
ently they  begin  to 
satisfy  the  intense  ni- 
trogen hunger  of  the 
clover,  alfalfa,  peas,  and  beans,  and  thus  the 
happy  family  lives  on  in  mutual  helpfulness. 
So  at  last,  down  in  this  borderland  of  life  has 
been  discovered  the  key  to  untold  riches  for  the 
farmer.  For  he  now  knows  the  importance  of 
root  nodules  and  their  bacteria,  and  can  trans- 
fer them  from  field  to  field,  or  he  can  get  from 


FIG.    7.— NODULE    BACTERIA 

These  irregular  shaped 
bacteria  were  artificially 
cultivated  from  the  nodules 
on  the  roots  of  leguminous 
plants. 


Agricultural  Conjurers  59 

the  Federal  Government,  or  from  State  agri- 
cultural or  other  laboratories,  artificial  living 
cultures  of  these  wonder  working  germs  with 
which  he  may  inoculate  his  field.  Then  he 
may  leave  them  in  the  rootlets  of  his  crops 
to  conjure  from  the  air,  by  day  and  by  night, 
this  precious  atmospheric  nitrogen.  This  the 
higher  plant  will  thrive  upon  and  thriftily  store 
away  for  the  future  uses  of  man  and  beast. 

There  are  certain  other  bacteria  in  the 
ground  which  can  fix  the  atmospheric  nitro- 
gen as  they  grow  and  so  enrich  the  soil.  In 
this  way  fields,  which  have  plenty  of  vege- 
table mould,  may  improve  when  allowed  to  go 
fallow  for  a  time.  But  the  various  forms  of 
nodule  bacteria  which  join  forces  with  the 
peas  and  beans  and  clovers  in  turning  air 
into  gold  are  the  more  dramatic  conjurers 
which  modern  science  has  presented  to  the 
farmer.  You  will  find  plenty  of  pictures  in 
the  books  which  deal  with  scientific  agricul- 
ture, showing  lean  beans  with  their  nodule- 
less  roots  beside  others,  the  nodular  and 
leafy  opulence  of  which  betokens  their  silent 
partnership  with  the  atmosphere. 


CHAPTER  VI 

BACTERIA  AS  MAN'S  INVISIBLE  FOES 

WE  have  seen  that  the  bacteria  in  general 
are  not  only  curious  and  interesting 
as  objects  of  study,  but  in  the  work  which  they 
are  ceaselessly  and  silently  doing  they  are 
absolutely  indispensable  to  the  continuance 
of  the  higher  forms  of  life  upon  the  earth. 
But  unfortunately  there  is  another  darker 
side  to  the  picture.  Among  the  myriads 
of  useful  as  well  as  harmless  bacteria,  we  have 
lately  learned  that  there  are  a  few  forms  which 
find  the  most  favorable  conditions  for  their 
life  and  growth  in  the  bodies  of  men  and  some 
of  the  higher  animals. 

Most  of  these  do  not  grow  well  in  nature 
as  other  bacteria  do,  nor  do  they  thrive  on 
ordinary  decomposing  organic  matter.  They 

look    very    much    like    the    more    common 

60 


Bacteria  as  Man's  Invisible  Foes    61 

harmless  bacteria,  some  being  little  balls, 
some  rods,  and  some  spirals.  Like  other 
bacteria,  they  grow  at  the  expense  of  the 
materials  with  which,  under  favorable  con- 
ditions, they  come  in  contact,  and  like  them 
they  produce  new  chemical  compounds  as  the 
result  of  their  life  processes.  When  they  get 
into  the  human  body,  the  different  species 
grow  in  different  ways,  and  produce  different 
kinds  of  chemical  compounds,  and  this  growth 
or  the  poisonous  substances  which  are  formed 
induce  disease. 

Bacteria  which  can  grow  in  the  body  and 
do  serious  harm  there  are  called  pathogenic 
or  disease-inducing  bacteria.  The  poisonous 
chemical  compounds  which  they  set  free  as 
they  grow,  are  called  toxines. 

Now,  before  we  try  to  comprehend  how 
disease  can  be  induced  by  bacteria,  we  ought 
to  understand  what  disease  is. 

We  have  seen  in  the  first  chapter  that  the 
human  body  is  made  up  of  several  commu- 
nities of  cells,  each  community  having  ac- 
quired the  power  of  doing  some  special  thing 
for  the  good  of  the  body  as  a  whole,  and  that 


62  The  Story  of  the  Bacteria 

these  cell  communities  are  all  co-ordinated  so 
as  to  act  in  harmony.  We  have  seen  that 
these  cell  communities  which  make  up  this 
wonderful  mechanism  are  all  originally  de- 
rived from  a  single  living  cell,  the  ovum. 

What  this  mysterious  thing  is  which  we  call 
life,  which  from  the  original  cell,  the  ovum, 
is  imparted  to  all  the  myriad  specialized  cells 
which  springs  from  it  as  the  body  grows;  what 
it  is  which  determines  that  from  one  of  two 
cells  which  under  the  most  powerful  of  micro- 
scopes look  exactly  alike  there  shall  develop 
a  man,  and  from  the  other  an  animal,  we 
simply  do  not  know.  We  theorize,  we  specu- 
late, we  draw  analogies,  we  give  names,  but 
at  the  end  we  conclude  that  we  must  wait  still 
for  more  light.  We  do  know,  however,  that 
this  self -built  cellular  mechanism,  the  body, 
which  is  alive,  has  in  it  the  power  of  self- 
renewal:  the  power,  when  once  started,  to 
go  on  doing  the  various  things  for  which  it  is 
fitted  for  a  time,  provided  the  proper  external 
and  internal  conditions  are  maintained.  But 
sooner  or  later  the  machinery  begins  to  creak 
and  tremble,  sometimes  in  one  part,  sometimes 


Bacteria  as  Man's  Invisible  Foes    63 

in  another,  sometimes  everywhere,  and  grad- 
ually or  suddenly  that  combination  of  activ- 
ities which  we  call  life  disappears,  and  the 
worn-out  mechanism  for  the  first  time  since 
it  came  into  being  is  still.  This  is  death. 
There  is  no  disease,  but,  as  we  are  apt  to 
say — not  because  it  means  much,  but  because 
we  think  we  must  say  something, — an  ex- 
haustion of  the  vital  forces.  The  mechanism 
is  worn  out,  and  so  can  no  longer  develop  out 
of  food  and  air  the  self-renewed  impelling 
force.  It  is  death  from  old  age.  But  this  is 
comparatively  infrequent. 

If  the  proper  food,  air,  and  surroundings 
are  maintained,  the  various  co-ordinated  cell 
communities  which  we  call  liver,  brain,  kid- 
neys, lungs,  integument,  and  so  forth,  pro- 
vided^they  are  properly  set  going  in  the  first 
place,  have  not  only  the  power  to  go  on  doing 
their  work,  but  they  have  a  well  marked 
capacity  for  overcoming  and  resisting  dele- 
terious agencies  of  one  kind  and  another, — 
a  sort  of  health  inertia.  The  muscle  cells 
do  make  shift  to  contract  even  though  their 
food  supply  be  temporarily  scanty;  the  blood 


64          The  Story  of  the  Bacteria 

cells  will  carry  a  certain  amount  of  oxygen 
in  their  ceaseless  rounds  of  visits  to  the  tissues, 
though  the  air  from  which  they  get  it  through 
the  lungs  be  as  foul  and  meagre  as  it  is  in 
some  of  our  fashionable  theatres  and  churches 
and  school-rooms.  And  if  certain  cells  or 
groups  of  cells  should  be  forced  to  work  awry, 
they  always  tend  to  get  back  to  their  proper 
business  and  conditions,  even  against  great 
obstacles,  just  as  soon  as  they  can. 

Even  when  large  numbers  of  cells  or  cell 
groups  are  entirely  removed  from  the  com- 
munity, as  by  an  injury,  new  cells  can  form 
out  of  those  which  are  left,  or  the  duties  of 
the  lost  cells  are  assumed  and  may  be  per- 
manently maintained  by  their  fellows.  Pa- 
triotism and  esprit  du  corps  are  very  markedly 
typified  in  the  cell  communities  which  to- 
gether constitute  the  republic  or  common- 
wealth called  the  body. 

When  important  cell  communities  are  seri- 
ously injured  or  changed  in  structure  so  that 
they  cannot  do  well  the  things  which  they 
ought  to  do,  or  when  they  fail  to  act  in  har- 
mony, through  some  fault  of  their  own  or  some 


Bacteria  as  Man's  Invisible  Foes    65 

disorder  in  the  co-ordinating  mechanism,  the 
failure  in  what  we  may  term  the  rhythm 
of  the  body's  activities  constitutes  what  we 
call  disease. 

The  part  which  may  be  the  seat  of  the  dis- 
ease is  as  varied  as  are  the  organs  and  tissues 
of  which  the  body  is  composed. 

The  disturbances  in  the  activities  of  the 
body  which  result  from  these  changes  in  the 
structure  and  action  of  the  various  parts  have 
been  so  long  studied  that  the  educated 
physician  is  usually  able  to  tell  from  certain 
irregularities  of  the  body's  activities  what  part 
or  parts  it  is  which  are  affected.  In  many 
cases  the  physician  does,  in  some  he  does  not, 
know  what  is  the  exact  cause  of  the  disturb- 
ance. In  some  cases,  when  the  cause  of  the 
disturbance  is  known,  he  can  remove  it  either 
by  directing  a  change  in  the  habits  or  by 
the  administration  of  drugs,  and  then  the  ten- 
dency of  the  cell  communities  of  the  body  to 
get  back  into  their  proper  condition  of  them- 
selves alone  will  restore  health.  Sometimes 
this  inherent  tendency  is  aided  by  the  use  of 
medicines.  Most  of  the  body's  disturbances 


66  The  Story  of  the  Bacteria 

tend  to  pass  away  of  themselves  after  a  longer 
or  shorter  period,  if  they  are  not  so  severe  as 
to  destroy  life.  Under  these  conditions  the 
duty  of  the  physician  may  be  only  to  aid 
the  body  by  food  and  air  and  proper  regimen 
in  the  work  which  it  is  doing  itself.  And  so 
through  the  long  list  of  ills  which  come  upon 
the  human  frame  from  known  or  unknown 
causes  the  wise  physician  guides  and  aids  the 
natural  recuperative  tendencies  of  the  body 
cells. 

Among  all  the  varied  changes  in  structure 
and  disturbance  in  activities  of  the  body 
which  thus  constitute  disease  there  are,  as  we 
have  seen,  several,  and  these  most  important 
ones,  which  have  recently  been  proven  to  be 
caused  by  bacteria.  To  some  of  these  we 
must  now  turn  our  attention  so  as  to  learn  how 
the  disturbances  are  brought  about,  and  what 
we  may  do  for  ourselves  to  avoid  them. 

But  before  we  enter  the  domain  of  the  doc- 
tors, let  us  devote  a  moment  to  their  shib- 
boleths, by  which  it  may  be  known  whether 
we  are  of  the  elect  or  only  dabblers. 

A  disease  which  is  incited  by  the  entrance 


Bacteria  as  Man's  Invisible  Foes    67 

into  the  body  and  proliferation  there  of 
pathogenic  micro-organisms  is  called  an  in- 
fectious disease;  the  organisms,  the  infective 
agents.  These  organisms  are  most  frequently 
bacteria,  but  other  minute  plants,  such  as 
yeasts  and  animals  called  protozoa,  are 
sometimes  to  blame. 

Each  infectious  disease  has  its  special 
features  by  which  the  doctor  knows  it. 
These  features  depend  upon  the  species  of  the 
invading  germ,  its  way  of  growing,  the  poison 
it  sets  free,  the  length  of  its  life  span.  But 
the  body  cells  have  their  particular  vulnera- 
bilities to  microbic  invasion  and  poisons. 
So  that  in  one  case  it  is  the  nervous  system, 
in  another  the  lungs  or  the  blood  or  the 
digestive  system  which  especially  suffers. 
Moreover,  as  one  rose  is  redder  than  another, 
or  one  aromatic  plant  more  pungent  than  its 
fellow,  so  in  one  case  the  germs  which  gain 
access  to  the  body  may  involve  a  more 
potent  poison  than  do  those  of  the  same 
species  but  of  another  strain,  and  then  the 
disease  may  be  more  virulent  in  type.  So 
also  an  individual  may  at  the  time  of  in- 


68  The  Story  of  the  Bacteria 

fection  be  more  susceptible  than  is  usual  to 
the  ravages  of  the  invader  and  thus  be  the 
victim  of  a  graver  form  of  the  disease. 

Infectious  diseases  of  the  type  of  small-pox, 
measles,  and  scarlatina,  whose  infective  agents 
are  easily  transmitted,  are  called  contagious. 
When  it  is  said  of  an  infective  disease  that 
it  is  more  or  less  readily  communicable,  it  is 
really  meant  that  the  infective  agent  is 
communicable,  not  the  disease.  For  disease 
is  always  a  process  of  the  body  and  not  a 
thing,  and  so  cannot  be  transmitted. 

The  elder  folk  were  wont  to  think  of  diseases 
as  some  sort  of  demons  or  evil  spirits  which 
attacked  the  body  or  took  possession  of  it, 
and  tried  to  banish  these  by  rattles,  drums, 
or  songs  and  incantations,  as  some  of  our 
North  American  Indians  do  to-day.  Though 
we  know  that  disease  is  not  a  thing  but  a 
disturbance  of  the  body  processes,  we  still 
speak  of  disease  as  attacking  the  body.  We 
say  "the  man  was  attacked  by  a  severe 
dyspepsia  after  eating  hot  plum  pudding. " 
But  it  was  really  not  the  dyspepsia,  it  was  the 
plum  pudding  which  attacked  the  man. 


Bacteria  as  Man's  Invisible  Foes    69 

Dyspepsia,  the  disease,  was  only  the  process 
of  reaction  or  defence  against  the  pudding. 

So  if  we  choose  to  be  dramatic  in  our  speech 
we  may  still  say  that  disease  attacks  a  man. 
But  let  us  hold  it  in  the  back  of  our  heads, 
that  we  do  not  really  blame  the  disease  but 
the  bacteria  or  other  factors  which  have  set 
it  going. 

It  is  well  to  do  this,  not  only  for  the  sake 
of  clearness  of  conception,  but  because  when 
we  try  to  cure  or  prevent  disease,  it  is  the  incit- 
ing factors  which  we  must  strive  to  control, 
and  not  only,  or  chiefly,  the  symptoms,  which 
characterize  but  do  not  constitute  the  disease. 
For  in  a  large  proportion  of  cases  the  symp- 
toms of  disease  are  only  the  marks  of  the 
efforts  of  the  body  to  protect  itself  against 
some  offending  condition  or  invading  thing. 
Fever  and  pain,  cough  and  headache,  the 
halting  appetite  and  laboring  heart — these 
may  all  be  only  signs  of  wholesome  resistance 
to  damage,  or  warnings  against  improper 
or  unsafe  modes  of  life. 

I 


CHAPTER  VII 

THE   BACTERIA  OF  WOUNDS  AND  OF  SURGICAL 
DISEASES 

ONE  of  the  greatest  dangers  associated 
with  injuries  and  wounds  of  the  body, 
whether  inflicted  by  accident  or  made  by  the 
knife  of  the  surgeon  in  necessary  operations, 
is  the  liability  to  what  is  known  as  blood 
poisoning. 

So  great  is  this  danger,  that  in  earlier 
wars  a  great  many  more  lives  were  usually 
lost  from  blood  poisoning  than  by  bullets 
or  cannon-balls.  The  cause  of  this  form  of 
disease,  which  is  so  apt  to  complicate  wounds, 
was  for  a  long  time  unknown.  Then,  as 
these  wounds  were  apt,  in  blood  poisoning, 
to  be  foul  and  bad-smelling,  it  was  concluded 

that  the  trouble  might  be  that  dirt  or  filth 

70 


Wounds  and  Surgical  Diseases     71 

of  some  sort  got  into  them  and  so  set  up  the 
disease. 

What  the  particular  thing  was,  whether 
bacteria  or  something  else,  which  so  gained 
entrance  to  the  body,  ho  one  knew.  But  the 
surgeons  did  not  wait  until  they  should  know 
all  about  the  cause  of  the  trouble,  but  began 
to  apply  to  the  wounds  such  materials  as 
would  actually  kill  germs,  or,  at  any  rate, 
keep  the  wounds  free  from  putrefactive 
changes.  Carbolic  acid,  dissolved  in  water, 
was  found  to  be  efficient  in  this  way  in  washing 
the  wounds. 

Then,  as  it  seemed  more  and  more  as  if  the 
trouble  were  due  to  living  germs  falling  upon 
the  wounds  from  the  air  with  the  dust,  it 
became  the  practice,  when  surgical  operations 
were  being  done  or  wounds  dressed,  to  spray 
carbolic  in  the  air  about  the  operator's  hands 
and  over  his  instruments  and  upon  the  wounds, 
and  when  the  bandages  were  put  on  to  seal 
them  in  tightly,  so  that  no  germs  could  gain 
access  to  the  wound  while  the  healing  went 
on.  All  this  time  the  particular  species  of 
bacteria  which  produced  the  trouble  remained 


72          The  Story  of  the  Bacteria 

entirely  unknown;  indeed,  it .  was  only  an 
hypothesis  that  the  disease  was  due  to  germs 
at  all. 

A  great  deal  of  careful  laboratory  work  has, 
however,  been  done  on  this  subject,  and  a 
great  many  animal  experiments  made,  so  that 
now  we  know  not  only  that 
blood   poisoning    but    boils, 
abscesses,     erysipelas,     and 
many  other  less  serious  in- 
flammations  are  induced  by 
bacteria.      We   have    found 

FIG.     8. — STREPTO-  c        .*  ,-,  ... 

coccus  PYOGENES  out»  furthermore,  that  there 
are  two  particular  species 
which  cause  the  trouble  in  the  great  majority 
of  cases. 

Both  of  these  bacteria  are  little  balls  or 
micrococci.  One  of  them,  as  it  grows,  tends 
to  form  chains,  and  so  is  called  Streptococcus 
(Fig.  8) ;  the  other  tends  to  group  itself  in 
clusters  a  little  like  a  bunch  of  grapes,  and 
so  is  called  Staphylococcus  (Fig.  9). 

Now,  it  has  been  further  found  that  these 
two  forms  of  bacteria  are  quite  abundant 
where  people  are  gathered,  mostly  in  dirty 


Wounds  and  Surgical  Diseases      73 

places;  sometimes  where  the  healthy,  but 
especially  where  sick  people  are  crowded 
together,  as  in  hospitals.  They  are  found  in 
small  numbers  floating  with  the  dust  in  the 
air,  where  dust  lodges,  and  often  in  the 
mouths  and  on  the  cloth- 
ing of  the  people  them- 
selves. 

It  is  thus  evident  how  £j/* 

the  wound  diseases,  such  Jb  -f*  +    9* 

as  blood  poisoning,  can 

-  f.  .,  FIG.    9- — STAPHYLO- 

come  about,  for  wherever  coccus  PYOGENES 
infective  dust  falls  on  the 
open  surfaces  of  the  wounds  or  on  any  thing 
which  comes  in  contact  with  them,  or  if  the 
hands  of  surgeons  or  others  who  dress  wounds 
are  not  free  from  the  dangerous  bacteria  these 
may,  if  not  destroyed,  commence  to  grow, 
and  not  only  by  the  poisonous  materials 
which  they  form  as  they  grow,  interfere  with 
the  healing  of  the  wounds,  but  they  may  get 
into  the  blood  and  be  carried  to  various 
parts  of  the  body,  there  sometimes  producing 
fatal  results. 

The  modern  surgeon,  in  the  many  beneficent 


74  The  Story  of  the  Bacteria 

operations  which  he  performs,  is  not  so  much 
concerned  about  the  bacteria  which  may  fall 
upon  the  wounds  from  the  air,  as  he  is  about 
those  germs  which  may  be  upon  the  hands 
or  face,  or  may  come  from  the  mouth  or  nose 
or  from  some  insignificant  pustule  or  a  boil 
of  himself  or  the  attendants,  because  these 
are  more  apt  to  be  fully  virulent  than  are  bac- 
teria which  have  been  dried  and  sunburned  in 
the  dust.  So  he  does  not  use  disinfectants  as 
much  as  was  formerly  the  case,  but  sees  to  it 
that  the  seat  of  operation  in  the  patient,  and 
the  hands  of  the  attendants  and  all  instru- 
ments, towels,  bandages,  etc.,  which  may  touch 
the  wounds,  are  freed  beforehand,  as  nearly 
as  possible,  from  all  contaminating  germs. 

This  is  the  aseptic,  which  has  supplanted 
the  antiseptic  surgery.  The  aim  is  to  keep 
bacteria  out  of  wounds,  rather  than  to  try 
to  kill  them  with  antiseptics,  after  they  have 
been  allowed  to  get  in.  Clean  white  aprons, 
caps  and  gowns,  rubber  gloves,  or  fresh 
scrubbed  hands,  sterile  instruments  and  dress- 
ings— these  are  the  insignia  of  aseptic  surgery, 
whose  watchword  is  cleanliness. 


Wounds  and  Surgical  Diseases     75 

It  is  one  of  the  greatest  practical  triumphs 
of  science  in  modern  times  that  the  surgeon 
can  now  so  carefully  plan  out  his  operations 
and  treatment  of  wounds,  that  not  only  is 
blood  poisoning,  as  it  used  to  prevail  but  a  few 
years  ago,  the  greatest  rarity  among  edu- 
cated and  skilful  surgeons,  but  the  most  ex- 
tensive operations,  such  as  opening  the  great 
cavities  of  the  body,  may  now  be  done,  when 
they  are  necessary  to  save  life  or  make  it 
endurable,  with  very  little  risk  of  the  dangers 
which  formerly  attended  such  procedures. 

Childbed  fever,  which  in  former  times 
claimed  so  many  victims  under  especially 
pitiful  circumstances,  and  which  used  some- 
times to  spread  with  frightful  rapidity  among 
women  whose  confinement  took  place  in  hos- 
pitals, is  now  of  comparatively  rare  occur- 
rence, because  the  educated  physician  knows 
what  the  particular  element  of  danger  is  and 
how  to  avoid  and  combat  it.  For  it  has  been 
found  that  childbed  fever  is  really  a  form  of 
blood  poisoning,  due  to  the  same  germs  as 
induce  the  disease  in  ordinary  wounds. 

Dr.  Oliver  Wendell  Holmes,   early  in  his 


76  The  Story  of  the  Bacteria 

career,  became  convinced  that  the  poison 
causing  childbed  fever  could  be  carried  on 
the  clothes  of  the  physician  from  one  patient 
to  another.  What  the  poison  was  he  could 
not  even  fairly  conjecture,  but  of  the  fact  he 
was  certain.  In  spite  of  much  opposition 
and  ridicule  he  urged  his  views,  and  many 
lives  were  ultimately  saved  and  epidemics 
stayed  because  of  his  persistency  in  making 
known  his  facts.  To-day  we  not  only  know 
that  all  that  he  urged  was  true,  but  the 
poison  which  he  assumed  but  could  not  see 
has  been  proved  to  be  bacteria,  and  we  can 
now  cultivate  them  in  tubes  and  know  exactly 
what  will  most  surely  destroy  them.  While 
literature  owes  much  to  the  wit  and  cleverness 
of  the  genius  of  the  breakfast-table,  science 
and  humanity  are  not  less  debtors  to  the  zeal 
and  pertinacity  of  the  young  doctor,  who  still 
declared  for  his  beliefs,  though  his  more  aged 
and  then  more  renowned  confreres  applied  to 
him  many  terms  of  opprobrium  and  disrespect. 
Now  let  us  look  a  little  more  closely  at 
the  way  in  which  these  tiny  organisms  induce 
inflammation,  suppuration,  or  the  formation 


Wounds  and  Surgical  Diseases      77 

of  pus  and  blood  poisoning.  We  have  seen 
in  the  first  chapter  that  although  most  of  the 
cells  of  the  body  have  assumed  special  forms 
and  powers  as  the  body  develops  out  of  its 
embryonic  period,  there  are  some  cells  which 
scarcely  seem  to  have  got  beyond  the  stage 
in  which  the  simplest  of  the  unicellular 
organisms,  such  as  the  amoeba,  belong.  The 
most  prominent  of  these  lowly  organized  cells 
in  the  body  are  the  white  blood-cells  or, 
leucocytes  as  they  are  called.  (See  Plate  XL) 
Under  ordinary  conditions  these  go  circling 
round  in  the  blood-vessels  along  with  the  red 
blood-cells,  or,  crawling  out  of  the  blood- 
vessels, slowly  make  their  way  about  in  the 
smaller  spaces  in  the  tissues.  All  the  things 
they  do  under  these  circumstances  we  do 
not  know.  But  they  are  at  any  rate  the 
great  scavengers  of  the  body.  When  they 
come  across  a  particle  of  worn-out  or  foreign 
material  in  the  tissues,  they  take  it  into 
themselves,  just  as  amoeba  does  its  food  in 
water,  and  either  digest  it  or  carry  it  back 
to  those  parts  of  the  body  in  which  waste 
material  is  systematically  disposed  of. 


78  The  Story  of  the  Bacteria 

But  let  an  injury  such  as  an  open  wound 
occur,  and  the  whole  attitude  of  these  leuco- 
cytes changes.  They  get  out  of  the  blood- 
vessels with  all  speed,  in  greater  or  less 
numbers  as  the  occasion  may  demand,  and 
gather  about  the  edges  of  the  wound,  and  after 
a  time  they,  together  with  some  other  cells  of 
the  injured  tissue,  form,  with  the  aid  of  the 
blood-vessels  near  by,  a  mass  of  new  tissues, 
which  replaces  that  which  was  lost  by  the 
injury,  and  so  permanently  binds  the  edges 
of  the  wound  together.  Sometimes  these 
white  blood-cells  gather  in  much  greater 
quantities  about  the  wound  than  is  necessary, 
and  then  they  are  thrown  off  with  some  fluid 
in  the  form  of  a  material  which  we  call  pus. 

Now  to  come  back  to  the  bacteria  which 
we  are  studying.  When  these  bacteria  get 
into  the  tissues,  they  may  begin  to  grow,  and 
as  they  do  so  they  produce  a  small  amount 
of  a  poison  which  we  call  a  toxine.  This 
poison  acting  injuriously  on  the  tissues  where 
it  is  formed,  the  white  blood-cells  gather  about 
it  just  as  they  would  about  a  wound.  If  the 
bacteria  continue  to  grow  and  multiply,  the 


Wounds  and  Surgical  Diseases     79 

white  blood-cells  may  accumulate  more  and 
more  and  die,  the  tissues  may  break  down,  and 
so  an  abscess  may  be  formed.  Sometimes 
the  germs  get  into  the  blood  and  are  carried 
to  various  parts  of  the  body,  and  wherever 
they  lodge  abscesses  may  be  formed,  and  this 
constitutes  one  of  the  most  dreaded  forms  of 
blood  poisoning. 

Now  what  do  the  white  blood-cells,  the 
leucocytes,  accomplish  under  these  circum- 
stances? 

There  is  good  reason  to  believe  that  the 
resisting  capacity  of  the  body  to  the  incur- 
sions of  these  living  bacteria  is  largely  resident 
in  the  lowly  organized  cells,  which  in  carrying 
on  their  simple  cellular  activities  assume  the 
role  of  defenders  of  the  body  against  the  bac- 
terial invaders.  If  the  conditions  are  fa- 
vorable for  them  the  white  blood-  and  other 
cells  may  get  the  upper  hand  of  the  bacteria 
and  stop  their  growth  or  kill  them  all  off  and 
thus  avert  the  danger.  If,  on  the  other  hand, 
the  cells  are  not  vigorous  enough  to  resist 
the  poison  set  free  by  the  bacteria  and 
themselves  succumb  to  its  influence,  the 


8o          The  Story  of  the  Bacteria 

way  is  opened  to  the  spread  of  the  infecting 
germs. 

In  a  later  chapter  on  the  safeguards  of  the 
body  we  shall  look  a  little  more  closely  at 
this  significant  battle  of  the  cells  in  various 
infectious  diseases. 

It  sometimes  happens  that  so  extensive  a 
growth  of  the  bacteria  occurs  in  some  local 
region  of  the  body  and  so  much  of  the  soluble 
poison  is  produced  that  although  the  bacteria 
may  not  themselves  get  generally  distributed 
the  poison  which  they  furnish  may  enter  the 
circulation,  and  so  produce  in  distant  parts  of 
the  body  most  serious  disturbance  or  even 
cause  death.  The  condition  in  which  bac- 
terial poisons  are  circulating  in  the  blood 
is  called  toxcemia.  When  the  bacteria  them- 
selves escape  from  their  primary  seat  of 
growth  and  with  their  toxins  gain  access  to 
the  blood  the  condition  is  called  septiccemia 
or  bactericemia- 

These  bacteria  of  suppuration  apparently 
do  no  harm  when  they  lodge  upon  the  unin- 
jured surface  of  the  body,  but  only  when 
they  get  into  the  tissues  through  an  injury 


Wounds  and  Surgical  Diseases      81 

or  lodge  upon  surfaces  of  the  respiratory  or 
digestive  tract  or  in  the  heart  and  blood- 
vessels which  are  already  the  seat  of  disease. 
When  they  get  into  the  hair  follicles  of  the 
skin,  however,  under  certain  conditions  they 
may  incite  boils. 

This  is  in  brief  the  story  of  the  bacteria 
which  most  frequently  induce  the  common 
inflammations  of  the  tissues,  the  compli- 
cations in  the  healing  of  wounds,  and  the 
varying  phases  of  blood  poisoning. 

As  pus  in  greater  or  less  quantity  is  apt 
to  be  produced  under  these  circumstances, 
these  bacteria  are  called  the  pus-forming  or 
pyogenic  bacteria  so  they  are  named  Staphy- 
lococcus  pyogenes  and  Streptococcus  pyogenes. 
(See  Figs.  8  and  9.) 

Some  other  bacteria  may  occasionally  in- 
duce similar  disorders  in  the  body,  but  those 
which  have  been  described  are  the  most 
common  and  important. 

In  addition  to  their  power  of  inciting  in- 
flammation alone  or  together,  the  staphy- 
lococcus  and  the  streptococcus  are  so  common 
among  city  folks  and  those  who  live  crowded 


82  The  Story  of  the  Bacteria 

together,  that  they  are  frequently  present  in 
other  bacterial  diseases  which  they  may 
seriously  complicate. 

The  effects  which  the  pyogenic  as  well  as 
other  disease-inducing  bacteria  may  produce 
in  the  body  vary  considerably  under  different 
conditions.  Sometimes  the  general  state  of 
the  body  is  such  that  it  seems  to  furnish  very 
favorable  soil  for  their  proliferation  or  is 
especially  vulnerable  to  their  action.  Some- 
times the  particular  germs  which  gain  access 
seem  to  be  especially  virulent,  perhaps  from 
their  inherent  vigor  or  from  conditions  which 
we  know  nothing  about.  We  are  in  these 
diseases  dealing  with  poisons  for  the  human 
body,  but  with  self -propagating  poisons  which 
from  an  almost  infinitesimal  amount  may  grow 
to  such  quantities  as  in  the  end  can  fairly 
overwhelm  it. 

The  habits  of  scrupulous  cleanliness  afford 
our  best  protection  against  the  intrusions  of 
these  germs.  In  vigorous  general  health  lies 
our  strongest  resistance  to  their  incursions. 


CHAPTER  VIII 

THE   BACTERIA   OF   CONSUMPTION,    OR 
TUBERCULOSIS 

MORE  than  one  seventh  of  all  the  people 
who  die  are  carried  off  prematurely 
by  consumption,  or  tuberculosis.  But  it  is 
only  recently  that  we  have  had  any  definite 
knowledge  as  to  its  cause.  For  a  great  while 
physicians  have  known  a  great  deal  about  the 
disease.  They  have  become  very  expert  in 
detecting  its  advent  and  in  tracing  its  course, 
and  came  long  ago  to  know  but  too  well 
whither  it  tended.  It  was  usually  regarded 
as  hopeless,  and  its  treatment  was  entered 
into  rather  for  humanity's  sake  than  in  the 
expectation  of  inducing  a  cure.  To-day  the 
aspect  of  affairs  has  greatly  altered.  We 
know  through  the  illuminating  discoveries 
of  Koch  that  tuberculosis  is  caused,  and 

83 


84          The  Story  of  the  Bacteria 

caused  alone,  by  exceedingly  minute,  rod- 
shaped  bacteria — bacilli — which,  in  one  way 
or  another,  gain  access  to  the  body  (Fig.  10). 
When  there,  if  the  conditions  are  favorable, 
they  tend  to  grow,  and  as  they  do  so  there 
form  about  them  little  masses 
of  new  tissue,  which  are  called 
tubercles.  The  most  com- 
mon seat  of  the  disease  is  the 
lungs,  but  it  may  occur  in 
FIG.  IO.-TUBERCLE  any  part  of  the  body. 

The  tubercles  which  form 
From  the  sputum     in  the  lungs  are  usually  lim- 

of  a  person  having      ited  ^  &  small  ft^     t 

tuberculosis  of   the 

lungs.  the  top  of  the  chest.     But 

sometimes  they  are  widely 
scattered  through  the  lung.  Plate  VI.  shows 
numerous  tubercles — the  little  white  spots — • 
in  a  human  lung. 

Where  the  tubercles  form  the  tiny  air  cham- 
bers are  destroyed  and  the  lung  becomes 
solid.  This  is  shown  in  Plate  VII.  The  dark 
mass  just  beneath  the  surface  of  the  lung  is 
the  tubercle.  Around  it  are  the  air  chambers 
quite  open  and  useful. 


The  Bacteria  of  Consumption       85 

But  after  a  while,  the  poisons  of  the  tubercle 
bacilli  destroy  these  new-formed  tubercles  as 
well  as  the  lung  itself  and  then  they  often  be- 
come friable  and  break  down.  Thus  cavities 
of  considerable  size  may  form  in  the  lungs. 
Plate  VIII.  shows  a  series  of  such  cavities. 

On  the  walls  of  these  cavities  the  tubercle 
bacilli  often  grow  in  enormous  numbers  and 
as  the  cavities  usually  connect  with  the 
bronchial  tubes,  the  bacilli  may  be  cast  out 
in  the  sputum. 

We  know  that  tuberculosis  is  never  caused 
by  any  other  thing  than  the  tubercle  bacillus, 
and  that  even  in  persons  predisposed  by  in- 
heritance or  otherwise  to  the  disease  it  cannot 
occur  unless  this  particular  germ  gets  into  the 
body  from  outside.  The  germ  itself  has  rarely, 
if  ever,  been  shown  to  be  directly  inherited. 
If,  therefore,  we  could  keep  this  particular 
germ  away  from  human  beings,  there  would 
be  no  more  tuberculosis,  no  matter  what 
the  inherent  tendencies  of  the  individual 
might  be. 

In  fact,  human  beings  in  general  are  very 
resistant  to  the  incursions  of  the  tubercle 


86          The  Story  of  the  Bacteria 

bacillus.  This  is  shown  by  the  fact  that 
physicians,  making  autopsies  upon  the  bodies 
of  large  numbers  of  persons  who  have  died 
from  accidents  or  diseases  other  than  tuber- 
culosis, have  found  that  nearly  every  adult 
has  at  some  time  in  his  life  had  some  small 
focus  of  tuberculosis.  This  his  body  cells 
have  so  successfully  and  promptly  controlled 
that  he  has  been  wholly  unaware  of  the  in- 
fection. But  while  this  shows  the  resisting 
capacity  of  human  beings  to  the  tubercle 
bacillus,  it  also  indicates  the  wide  distribution 
of  the  bacillus  in  the  places  which  man 
frequents. 

When  an  individual  recovers  from  tubercu- 
losis, the  bacteria  are  destroyed  and  the  new 
growth  which  is  called  the  tubercle  is  slowly 
converted  into  dense  tissue  like  a  scar.  Some- 
times the  body  cells  build  a  wall  of  scar 
tissue  around  the  bacilli  and  the  affected 
region  (Plate  VII.),  so  that  the  tuberculous 
process  may  lie  dormant  for  a  long  time. 

Now  where  do  tubercle  bacilli  come  from? 
Remember  that  they  do  not  grow  outside 
the  bodies  of  warm  blooded  animals,  except 


PLATE    VI. — TUBERCLES    IN    THE    LUNG 

In  this  case  myriads  of  turbercles  about  the  size  of  a  grain 
of  millet  are  scattered  through  the  lung.  This  form  of  the 
disease  is  therefore  called  "miliary  tuberculosis." 


The  Bacteria  of  Consumption       87 

in  the  artificial  cultures  of  the  bacteriologist 
(see  Plate  IX.).  So  we  need  not  look  to 
sewage,  polluted  water,  or  dirty  vegetables, 
or  rotting  stuff  of  any  kind  as  fruitful  sources 
of  distribution.  It  is  in  tuberculous  human 
beings  and  tuberculous  cattle  that  we  find 
the  great  sources  of  infection. 

Let  us  look  first  at  the  human  source.  The 
masses  of  new  tissue  which  form  in  the  lungs 
where  tubercle  bacilli  grow  are  not  well 
supplied  with  blood,  and  so  under  the  in- 
fluence of  the  poisons  which  the  bacilli  set 
free  as  they  grow  and  flourish  and  die  they 
are  apt  to  become  friable  and  break  down  and 
then  little  particles  of  them  containing  myriads 
of  living  virulent  germs  are  coughed  up  and 
discharged  in  the  sputum.  So  the  sputum 
of  persons  with  tuberculosis  of  the  lungs 
and  the  secretions  in  their  mouths  and  some- 
times the  nose  and  their  lips  often  swarming 
with  bacilli  are  the  immediate  sources  of 
distribution  of  these  sinister  germs. 

Now,  if  the  material  which  consumptive 
persons  cough  up  and  spit  out  were  always 
destroyed  at  once  by  being  burned  or  received 


88          The  Story  of  the  Bacteria 

into  a  dish  of  some  efficient  disinfectant,  one 
of  the  greatest  dangers  of  the  spread  of  the 
disease  would  be  removed.  But  unfortu- 
nately this  is  in  fact  very  rarely  done.  Thou- 
sands of  consumptives  are  walking  about  the 
streets  of  our  large  towns  or  visiting  places 
of  assembly,  who  discharge  the  infectious 
material  coughed  up  from  the  lungs  upon 
the  pavements  or  floors.  This  dries,  and 
shortly  is  ground  up,  and  takes  its  place 
among  the  rest  of  the  floating  dust  of  the  air. 
Essentially  the  same  thing  takes  place  in 
rooms  in  which  consumptives  are  confined, 
if  intelligent  precautions  are  not  taken  to 
destroy  or  convey  away  the  discharged  ma- 
terial. It  has  been  found  by  actual  experi- 
ment that  a  considerable  number  of  living 
tubercle  bacilli  may  be  lodged,  together  with 
other  dust  particles,  high  up  on  the  walls  of 
hospital  wards  in  which  consumptives  are 
unintelligently  cared  for,  in  situations  to 
which  they  could  haye  been  conveyed  only 
through  the  air  as  ordinary  dust  is.  The  same 
material  allowed  to  dry  on  handkerchiefs  may 
in  a  similar  way  become  a  source  of  danger, 


PLATE    VII. — A    TUBERCLE    IN    THE    LUNG — HEALED 

In  this  photograph  of  a  highly  magnified  tubercle, 
which  has  healed  by  the  formation  of  scar-like  tissue 
about  it,  one  sees  the  minute  air  chambers  of  the  lung 
surrounding  the  solid  tubercle.  At  the  site  of  the  tuber- 
cle the  air  chambers,  and  hence  the  usefulness  of  this 
portion  of  the  lung,  have  been  destroyed. 


The  Bacteria  of  Consumption       89 

not  only  to  others,  but  may  cause  a  fresh 
infection  of  the  patient  himself. 

Bacteria  never  rise  from  thoroughly  moist 
surfaces.  One  might  spread  a  thick  layer 
of  living  bacteria  of  any  kind,  no  matter  how 
infectious,  over  an  exposed  surface,  and, 
provided  it  was  kept  thoroughly  moist,  might 
breathe  with  impunity  the  air  sweeping  in 
strong  currents  over  it,  because  the  germs 
always  cling  most  tenaciously  to  such  sur- 
faces. Of  course  a  current  of  air  strong 
enough  to  sweep  the  particles  of  fluid  bodily 
off  from  their  position  would  be  efficient  in 
spreading  the  infectious  material.  The  im- 
portant point  which  this  statement  emphasizes 
is  that  the  breath  of  tubercular  persons 
is  not  infectious;  the  air  itself  passing  over 
the  moist  surfaces  of  the  respiratory  passages 
and  the  mouth  carries  no  germs.  The  act 
of  kissing,  however,  might  lend  itself  most 
efficiently  to  the  transmission  of  the  living 
bacilli. 

So  also  they  may  be  conveyed  through  the 
use  of  uncleansed  eating  utensils,  dishes,  hand- 
kerchiefs, towels,  etc.,  used  by  a  consumptive. 


90          The  Story  of  the  Bacteria 

There  is  another  way  in  which  tubercle 
bacilli  are  transmitted  which  though  less 
generally  recognized  is  in  some  respects  more 
significant  than  the  conveyance  by  dust  or 
contaminated  articles,  or  by  direct  contact 
of  the  sick  with  the  well,  and  this  is  by 
coughing  and  sneezing.  While  the  tubercle 
bacillus  can  remain  alive  for  some  time  when 
dried  in  dust,  it  becomes  less  and  less  virulent, 
and  strong  daylight  or  direct  sunlight  kills  it 
in  a  few  days  or  hours.  So  that  the  tubercle 
bacillus  in  ordinary  dust  tends  to  become  less 
and  less  a  menace. 

In  explosive  coughing  and  in  sneezing,  fine 
particles — in  sneezing  a  veritable  spray — 
may  be  sent  forth  for  several  feet  into  the  air. 
Now  in  these  particles  fully  virulent  tubercle 
bacilli  may  be  contained,  often  in  great  num- 
bers. The  fine  spray  of  sneezing  frequently 
floats  for  a  considerable  time  in  the  air  and 
may  be  breathed  in  by  others. 

Plate  X.  shows  a  Petri  plate  placed  three 
feet  from  the  face  during  a  vigorous  sneeze. 
The  colonies  growing  after  four  days  on  the 
surface  of  the  gelatin  show  how  many  living 


PLATE    VIII. — TUBERCULOUS    CAVITIES    IN    THE    LUNGS 

In  the  upper  parts  of  this  lung,  the  tuberculous 
tissues  have  been  destroyed,  broken  down  and  cast  ofr, 
leaving  rough  irregular  cavities  communicating  with 
the  bronchial  tubes.  In  the  walls  of  these  cavities  tu- 
bercle bacilli  thrive  and  may  be  discharged  in  large 
numbers  with  the  sputum. 


The  Bacteria  of  Consumption      91 

germs  were  widely  dispersed  in  the  air.  Of 
course  those  which  fell  upon  this  small  dish, 
three  inches  across,  form  but  a  small  proportion 
of  the  number  expelled. 

It  is  thus  clear  that  both  safety  and  decency 
require  that  in  coughing  and  sneezing,  the 
handkerchief,  or  at  need  the  hand,  should  be 
held  before  the  mouth  and  nose.  This  ob- 
vious rule  of  propriety  is  also  a  counsel  of 
security  under  all  circumstances,  since  the 
mouth  and  nose  of  many  persons,  not  tuber- 
culous and  not  even  themselves  ill,  contain 
infective  organisms  which,  gaining  a  foothold 
upon  more  vulnerable  individuals  may  lead 
to  serious  disease. 

Now  all  these  facts  are  extremely  disagree- 
able both  to  hear  about  and  to  tell,  and  they 
can  only  be  infinitely  distressing  to  the  vic- 
tims of  tuberculosis  and  to  their  friends  and 
associates;  but  all  the  same  they  are  facts, 
stubborn,  abiding,  and  significant.  The 
sooner  we  recognize  the  truth  that  every 
consumptive  person  may,  if  proper  precau- 
tions are  not  taken,  be  an  actual  and  active 
source  of  infection,  not  only  to  those  who 


92  The  Story  of  the  Bacteria 

immediately  come  in  contact  with  him,  but  to 
those  who,  either  where  he  is,  or  where  he 
has  been,  are  forced  to  breathe  dust-laden  air, 
the  better  will  it  be  for  all  concerned. 

Of  course  no  intelligent  person  would  infer 
from  this  statement  of  facts  regarding  the 
sources  of  infection  with  tubercle  bacilli 
through  the  air,  that  everybody  who  goes  upon 
the  street  or  enters  a  hospital  or  a  theatre 
is  going,  or  is  even  liable,  to  acquire  tubercu- 
losis. For,  in  the  first  place,  the  infecting 
material,  even  under  the  worst  conditions 
is  enormously  diluted  by  the  circulating  air 
and  the  tubercle  bacilli  are  killed  by  sunlight, 
so  that  the  individual  chances  of  coming 
in  contact  with  the  dangerous  material  are 
slight. 

In  the  second  place,  the  average  healthy 
individual  is  not  predisposed  to  the  disease 
at  all,  and  could  be  affected  only  under  es- 
pecially favorable  conditions.  Third,  the 
amount  of  infecting  material  is  apt,  in  trans- 
mission by  the  air,  to  be  small,  and  this  is  a 
condition  which  diminishes  the  chances  of 
danger  from  such  exposure. 


9 


PLATE    IX. — CULTURES    OF    THE    TUBERCLE    BACILLUS 

These  cultures  are  of  several  weeks'  growth  on  coagulated 
blood-serum.  They  were  derived  from  different  sources  and  the 
variations  in  growth  to  be  observed  mark  different  strains  of  the 
species. 


The  Bacteria  of  Consumption       93 

Finally,  every  individual  has  in  his  respira- 
tory tubes  an  arrangement  of  tiny  cells  whose 
free  surfaces  are  covered  with  little  hair-like 
processes  called  cilia.  These  are  ceaselessly 
waving  to  and  fro,  and  tend  to  sweep  up  and 
away  from  the  lungs  foreign  particles  which 
may  be  breathed  in  with  the  air.  But  not- 
withstanding all  these  conditions  which  serve 
to  guard  the  exposed  individual  against  the 
disease-producing  bacteria,  it  still  remains  true 
that  no  man  can  acquire  tuberculosis  without 
getting  into  his  body  this  particular  bacillus 
from  some  infected  individual  or  animal. 

Now  as  to  tuberculous  cattle  as  sources  of 
infection.  Formerly  the  meat  of  such  cat- 
tle, which  might  be  eaten  uncooked,  was  a 
noteworthy  menace.  But  the  State  and 
Federal  control  of  diseases  of  cattle, — whose 
health  by  the  way  excites  a  much  more  vivid 
interest  in  governmental  circles  than  does 
the  health  of  man, — is  now  so  effective  that 
we  need  not  consider  it  further  here.  But 
the  milk  of  tuberculous  cows  frequently  con- 
tains virulent  tubercle  bacilli  and  frequently 
comes  to  the  markets. 


94          The  Story  of  the  Bacteria 

Infection  from  this  source  is  more  common 
in  young  children  than  in  adults,  and  the 
bacilli  may  enter  the  system  through  the 
tonsils  or  through  the  bowels.  In  children 
the  infection  may  apparently  remain  latent 
for  years,  only  revealing  itself  in  small  nodules 
in  the  neck  or  chest  or  abdomen.  But  there 
is  evidence  that  in  later  life  these  local  seats 
of  infantile  tuberculosis  may  become  sources 
of  general  infection.  By  boiling  or  properly 
pasteurizing  the  milk  for  infants,  this  risk 
may  be  avoided. 

The  conclusions  which  almost  thrust  them- 
selves upon  us  from  what  we  have  thus  learned 
about  tuberculosis  are  very  plain.  Tubercu- 
lous meat  and  milk  ought  never  to  get  into 
the  markets.  Milk  contaminated  with  tu- 
bercle bacilli  may  be  rendered  harmless  by 
heat. 

It  would  be  very  difficult  to  stop  by  any 
sort  of  legal  enactment  the  spread  of  the 
tubercle  bacilli  by  means  of  the  air  or  by 
personal  contact  from  man  to  man.  But 
a  thorough  acquaintance  of  all  persons  with 
the  fact  that  a  consumptive  patient  may  be 


PLATE  X. — A  SNEEZE  PLATE  CULTURE 

See  the  explanation  in  the  text. 


The  Bacteria  of  Consumption      95 

a  source  of  actual  danger  to  all  about  him, 
unless  the  proper  precautions  are  adopted, 
would  do  much  to  lessen  the  evil. 

Steamship  and  railroad  companies  should 
be  obliged  to  furnish  separate  accommo- 
dations for  persons  thus  affected,  so  that  no 
well  person  should  ever  be  forced  in  the 
exigencies  of  travel  to  expose  himself  to  the 
liability  of  infection. 

Such  regulations  and  discriminations  as  are 
here  suggested  would  of  course  often  be 
extremely  annoying  to  the  victims  of  the 
disease  and  their  friends  as  well  as  to  all 
immediately  concerned.  But  some  such  un- 
derstanding must  be  come  to,  unless  people 
are  to  go  on  needlessly  dying  from  this  most 
important  disease. 

The  best  way  of  disposing  of  the  sputum 
of  consumptive  persons,  which,  if  allowed  to 
dry,  may,  as  we  have  seen,  become  the  source 
of  active  danger  to  themselves  as  well  as  to 
others,  is  by  burning. 

It  may  be  received  into  small  cheap  wooden 
or  pasteboard  boxes,  which  are  now  made  and 
sold  very  cheap  by  the  druggists,  and  which 


96          The  Story  of  the  Bacteria 

at  frequent  intervals,  together  with  their 
contents,  should  be  burned  in  the  stove, 
furnace,  or  fireplace.  When  handkerchiefs 
or  cloths  are  used  to  receive  the  material 
coughed  up,  these  should  be  either  burned  as 
early  as  possible,  or  soaked  for  several  hours 
in  a  five  per  cent,  solution  of  carbolic  acid 
and  then  boiled  and  washed.  But  the  use 
of  handkerchiefs  and  cloths  is  to  be  avoided 
for  this  purpose  as  much  as  possible,  because 
they  afford  most  favorable  conditions  for  the 
drying  and  distribution  of  the  infectious 
material. 

The  acts  of  coughing  and  sneezing  should 
be  made  innocuous  by  the  use  of  the  hand- 
kerchief. Utensils  used  by  consumptives 
should  be  separately  and  properly  cleansed 
and  boiled.  Kissing  by  consumptives  should 
be  avoided. 

But  while  we  are  thus  led  by  the  knowledge 
which  has  been  gained  of  the  tubercle  bacillus 
to  a  more  precise  notion  as  to  what  should  be 
done  to  prevent  the  spread  of  the  disease, 
what  has  the  accumulated  lore  to  offer  of  hope 
or  comfort  to  those  already  stricken?  In  the 


The  Bacteria  of  Consumption      97 

first  place,  the  physician  can  now  say 
positively  by  finding  the  bacilli  in  the  material 
discharged  from  the  lungs,  in  many  cases 
even  in  very  early  stages,  that  the  lung  is 
out  of  order. 

We  now  know  that  consumption  is  by  no 
means  a  hopeless  disease,  especially  if  it  be 
detected  in  its  early  stages.  We  know  that 
the  cells  of  the  body,  if  they  are  in  a  properly 
active  and  vigorous  condition,  have  a  ten- 
dency to  destroy  the  germs.  In  a  large  pro- 
portion of  cases  if  the  disease  be  early 
discovered,  the  wise  physician,  by  recommend- 
ing life  in  the  open  air,  improved  conditions  of 
hygiene,  proper  exercise  and  food,  along  the 
lines  which  Trudeau  has  spent  so  many  in- 
spiring and  fruitful  years  in  developing,  may 
hold  out  to  his  patient  a  good  hope  of  ultimate 
recovery  or  of  prolonged  and  comfortable 
life.  Patent  medicines  and  advertised  cures 
for  consumptives  are  one  and  all  futile, 
fraudulent,  and  pernicious. 

We  battle  to-day  with  a  known  and  com- 
prehensible foe,  and  no  longer  grope  in  the 
dark  after  a  mysterious  and  unknown  enemy. 


98          The  Story  of  the  Bacteria 

The  hope  of  the  enlightened  physician  looks 
out  towards  a  time  when  we  may  have  learned 
some  direct  and  efficient  means  of  destroying 
the  invading  germs  in  the  body,  or  neutral- 
izing its  poisons.  But,  in  the  meantime,  by 
aiding  the  body's  inherent  means  of  cure,  he 
feels  himself  no  longer  helpless. 

Finally  as  to  individual  measures  of  pre- 
vention. Remember  that  the  healthy  human 
body  is  not  good  soil  for  the  tubercle  bacillus. 
Keep  the  body  strong  and  well  by  good,  plain, 
properly  cooked  food  and  plenty  of  it,  and  by 
proper  exercise,  sleep,  and  recreation.  Look 
out  for  the  milk.  Avoid  dissipations  whether 
in  work  or  play  or  idleness  or  worry  or  drink 
or  tobacco.  Get  all  the  fresh  air  you  can. 
Let  your  breath  be  deep  and  strong.  Sleep 
with  the  windows  open.  Keep  clean.  Cul- 
tivate cheerfulness.  Don't  neglect  colds,  for 
while  they  do  not  directly  lead  to  consump- 
tion the  vigor  of  the  body  may  be  so  lowered 
by  their  long  continuance  as  to  be  more 
susceptible. 

Do  what  you  may  as  a  good  citizen  to  get 
the  people  educated  to  stop  promiscuous 


The  Bacteria  of  Consumption       99 

spitting,  to  care  for  the  discharges  of  tuber- 
culous persons,  to  let  the  sunlight  and  air 
into  living  rooms  and  assembly  places,  and 
suppress  the  dust  nuisance  indoors  and  out. 
Then  go  about  your  business  and  don't  fret 
over  tuberculosis. 

Of  course  not  all  persons  can  secure  all 
of  these  desirable  things.  But  most  persons 
can  secure  some  of  them.  When  in  doubt 
consult  the  doctor. 


CHAPTER  IX 

TYPHOID  FEVER  AND  ITS   RELATIVES 

^YPHOID  fever  is  one  of  the  serious  and 
common  diseases,  occurring  among  all 
classes  of  people,  which  is  definitely  known 
to  be  induced  by  bacteria.  The  germs  of 
this  disease  are  little  rods  or  bacilli  considera- 
bly larger  than  those  which  cause  tubercu- 
losis (Fig.  n). 

There  are  several  forms  of  low  fever,  and 
some  other  diseases  due  to  various  causes, 
which  considerably  resemble  typhoid  fever, 
and  are  not  infrequently  mistaken  for  it. 
But  genuine  typhoid  fever  is  caused  by  this 
particular  germ,  and  no  other,  and  is  never 
induced  in  any  other  way.  The  lower  animals 
do  not  have  typhoid  fever. 

The  typhoid  bacillus  is  not  known  to  grow 
outside  the  body  to  any  considerable  extent 


100 


Typhoid  Fever  and  its  Relatives  101 

except  in  milk  and  when  artificially  cultivated 
by  the  biologist  for  purposes  of  study.  But 
it  may  remain  alive  for  several  weeks  outside 
the  body  in  milk,  in  water,  in  the  soil,  or 
under  other  conditions. 

The  typhoid  germ  in  the  large  majority  of 
cases,  enters  the  body  with 
food  or  drink  by  the  intes- 
tinal canal.  When  it  gets 
into  the  intestines,  if  the 
conditions  are  favorable,  it 
multiplies,  and  enormous  FIG-  "-—THE  BA- 

i  r       ,1  CILLI  OF  TYPHOID 

numbers    of    the  germs  are  FEVER 

thus  sometimes  produced. 
Some  of  these  often  gain  access  to  the  blood 
and  to  certain  of  the  internal  organs,  as  the 
gall  bladder  and  urinary  bladder,  but  many  of 
them  either  complete  their  existence  in  the 
intestinal  canal,  or  are  cast  out  in  the  living 
condition  with  the  diarrhoeal  discharges  which 
so  constantly  accompany  this  disease  and  in 
the  urine. 

As  the  typhoid  bacilli  in  this  disease  grow 
and  multiply  in  the  bowels,  or  elsewhere, 
they  form  a  soluble  poison — toxin — which  is 


102        The  Story  of  the  Bacteria 

absorbed,  just  as  some  kinds  of  food  might 
be,  and  carried  to  various  parts  of  the  body, 
producing  effects  which  we  recognize  as 
symptoms  of  the  disease. 

The  great  and  important  source  of  in- 
fection— the  means  by  which  the  disease  is 
usually  spread — is  these  discharges  from  the 
bowels  and  the  urine  containing  the  living, 
virulent  typhoid  bacilli. 

Here  we  have  an  essentially  similar  con- 
dition of  affairs  to  that  in  tuberculosis,  namely, 
bacteria  of  a  particular  species  inducing  a 
disease  which,  without  them,  could  not  or 
does  not,  so  far  as  we  know,  occur  and  after 
inducing  the  disease  in  an  individual,  being 
discharged  alive  and  virulent  from  the  body. 
Here,  as  in  tuberculosis,  although  the  mode  of 
infection  is  somewhat  different,  if  all  the  dis- 
charges from  persons  suffering  from  the  dis- 
ease could  be  immediately  destroyed,  all 
danger  of  infection,  so  far  as  we  know,  would 
be  removed.  Typhoid  fever  is  thus  a  com- 
municable and  a  preventable  disease. 

Typhoid  fever  affects  man  alone,  and  he 
alone  forms  the  source  of  infection.  But, 


Typhoid  Fever  and  its  Relatives     103 

unfortunately,  the  bacteria  are  not  generally 
destroyed,  and  the  house-mates  of  the  patient, 
or  those  whose  water  or  milk  or  food  supply 
become  contaminated  directly  or  indirectly 
from  his  discharges  are  liable  to  succumb  to 
the  same  malady. 

But  there  is  another  significant  source  of 
virulent  typhoid  bacilli  which  has  only  re- 
cently become  known.  It  has  been  discovered 
that  long  after  complete  recovery  from  ty- 
phoid fever  the  urine  and  the  intestinal 
waste, — the  latter  even  for  many  years, — 
may  contain  the  bacilli,  which  apparently 
get  domesticated  in  the  gall  bladder  or  else- 
where, and  while  no  longer  harmful  to  their 
host,  are  yet  fully  virulent  for  others  should 
the  chances  of  communal  life  bring  them  into 
contact  with  food. 

Thus  to  a  single  cook  has  been  traced  the 
infection  of  twenty-six  persons  in  seven 
different  families  to  whose  gastronomic  exi- 
gencies she  uncleanlily  ministered.  A  threat- 
ening epidemic  of  typhoid  has  been  started 
by  a  person  concerned  with  the  milk  supply 
of  a  large  city  district,  though  he  had  not 


104        The  Story  of  the  Bacteria 

for  many  years  been  the  victim  of  typhoid. 
In  these  two  cases  cited,  the  bacteriologist 
was  able  to  cultivate  in  the  laboratory  from 
the  discharge  of  these  two  entirely  healthy 
persons  virulent  typhoid  bacilli  and  show 
that  these  were  present  in  enormous  numbers. 

Such  persons,  now  known  to  be  common 
among  convalescents  from  this  fever,  are 
called  "  typhoid  carriers. "  The  possibility  of 
danger  when  such  persons  are  concerned  with 
food  supplies  or  food  preparation  are  obvious. 

The  lesson  of  this  unpleasant  revelation  is 
that  our  standards  of  personal  cleanliness 
must  be  more  exacting,  if  we  are  to  be  reason- 
ably secure  against  chance  infection  from 
"  typhoid  carriers. " 

Altogether  the  probabilities  are  that  in  the 
majority  of  cases  the  typhoid-fever  germs  are 
most  frequently  carried  and  consumed  in 
milk  and  in  water  which  have  in  some  way 
been  polluted  by  human  waste  containing 
the  typhoid  germ. 

It  seems  quite  incredible,  when  put  down 
in  black  and  white  on  paper,  that  responsible 
and  sane  persons  of  ordinary  intelligence, 


Typhoid  Fever  and  its  Relatives     105 

knowing  that  typhoid  fever  is  caused  by  a 
living  germ,  knowing  that  this  is  thrown  off 
from  the  body  in  the  living  condition  and 
without  being  destroyed,  is  allowed  to  run 
through  the  sewer  pipes  into  the  nearest 
stream  or  lake,  should  for  an  instant  consent 
to  have  the  water  of  this  stream  or  lake  taken 
from  within  a  short  distance  of  the  sewer 
opening,  and  often  in  line  of  direct  current, 
and  distributed  in  their  houses  unpurified, 
and  used  upon  their  tables.  And  yet  it 
would  be  but  the  telling  of  old  stories  for  the 
writer  to  cite  case  after  case  in  which  this 
offence  against  common  decency,  to  say 
nothing  of  good  taste,  is  practised  under 
conditions  much  more  flagrant  than  these. 
And  then  Providence  or  Fate  is  shouldered 
with  the  responsibility  when  the  careless  or 
ignorant  persons  themselves,  or  the  innocent 
victims  of  their  criminal  neglect,  are  stricken 
with  typhoid  fever. 

Typhoid  discharges  thrown  upon  the  banks 
of  drinking  water  reservoirs,  or  streams,  in 
winter,  from  the  camps  of  repair  gangs,  have 
in  many  instances  been  washed  into  the  water 


io6        The  Story  of  the  Bacteria 

by  the  spring  floods  at  the  cost  of  many 
hundreds  of  lives. 

Milk  supplies  should  be  especially  guarded, 
because  milk,  when  not  kept  very  cold,  is  a 
good  culture  medium  for  the  typhoid  bacillus, 
so  that  a  slight  primary  contamination  may 
become  fairly  pestilential  before  the  milk 
reaches  the  consumer. 

Oysters,  which  unscrupulous  dealers  place 
in  sewage-polluted  water  to  grow  plump  so 
that  the  guise  of  freshness  may  impose  upon 
their  victims,  have  many  times  been  the 
cause  of  typhoid  fever. 

Direct  conveyance  of  the  bacilli  from  the 
patient  to  nurses,  attendants,  or  friends  should 
not  be  possible  with  reasonable  care. 

Typhoid  bacilli  may  remain  alive  in  ice  for 
many  weeks  though  they  gradually  die  out. 
It  is  therefore  not  without  risk,  as  it  certainly 
is  without  decency,  that  one  permits  the  use 
for  drinking  of  ice  which  has  been  cut  from 
sewage-polluted  waters. 

Flies,  which  have  access  to  typhoid  dis- 
charges, may  carry  and  deposit  upon  human 
food  to  which  they  next  address  their  in- 


Typhoid  Fever  and  its  Relatives     107 

dustries,  virulent  typhoid  bacilli  in  large 
numbers.  In  the  Spanish  American  war  there 
were  many  victims  of  gross  neglect  in  sanita- 
tion in  whose  destruction  red  tape  and  the 
common  house-fly  played  a  conspicuous  r61e. 
We  shall  consider  this  nefarious  insect  more 
at  length  in  a  later  chapter. 

Typhoid  discharges  should  always  be  ren- 
dered harmless  at  once  by  heat  or  be  disin- 
fected with  carbolic  acid  or  some  other 
effective  agent,  no  matter  where  they  are  to 
be  finally  disposed  of,  and  this  should  be 
done  whether  the  doctor  does  his  duty  in  the 
matter,  or,  as  is  sometimes  the  case,  neglects  it. 

So  long  as  the  excreta  of  typhoid  patients 
are  not  systematically  disinfected  but  are 
allowed  to  pass  into  sewers  and  cesspools, 
or  are  thrown  on  to  the  soil  whence  they 
pollute  watercourses;  so  long  as  a  high 
standard  of  personal  cleanliness  is  not  re- 
quired in  those  who  deal  with  milk  and  other 
food  supplies, — we  must  expect  that  this 
typhoid  fever,  which  is  a  disgrace  to  our 
boasted  civilization,  because  wholly  unneces- 
sary, will  flourish  here  and  there. 


io8        The  Story  of  the  Bacteria 
Dysentery 

There  is  another  bacillus  at  least  first 
cousin  to  the  typhoid  germ  to  which  is  at- 
tributable certain  forms  of  bowel  trouble  all 
the  world  over,  and  called  the  Bacillus 
dysenterice.  There  are  several  types  of  these 
small  pests.  They  are  transmitted,  as  are 
their  typhoid  relatives,  from  the  discharges 
of  patients  mostly  through  water,  milk,  and 
direct  contact,  or  by  flies.  Like  typhoid 
fever,  the  infectious  forms  of  dysentery  are 
filth  diseases  and  need  not  occur  with  proper 
attention  to  sanitation. 


CHAPTER  X 

ASIATIC  CHOLERA 

HISTORY  records  many  tragic  stories  of 
sudden  outbreaks  of  fatal  disease  which, 
spreading  like  wildfire  among  the  people,  have 
brought  untold  miseries  and  countless  deaths. 

In  early  times  these  frightful  whirlwinds  of 
disease  were  looked  upon  as  penal  visitations 
of  the  Supreme  Powers,  and,  in  the  utter 
panic  which  they  so  often  induced,  little  was 
done  in  the  way  of  studying  their  nature  or 
staying  their  progress. 

Among  the  more  important  of  these  tragic 
epidemics  which  have  been  experienced  and 
carefully  observed  since  science  has  with- 
drawn the  veil  of  superstition  from  them, 
stands  Asiatic  cholera. 

In  some  parts  of  the  world  this  disease  is 

constantly  present  and  claims  each  year  a 

109 


no        The  Story  of  the  Bacteria 

varying  number  of  victims.  But  Europe 
and  America  are  in  general  free  from  it,  save 
that  now  and  then,  coming  from  its  home  in 
the  Far  East,  it  sweeps  along  the  seaboard  or 
over  the  country,  bringing  in  a  greater  or 
less  degree  the  old-time  panic  and  misery 
and  death  in  its  train.  Occasionally  it  finds 
lodgment  upon  our  own  shores  and  has 
penetrated  into  the  interior. 

Now  up  to  within  a  few  years  we  have  not 
known  what  the  cause  of  this  disease  really 
was.  It  seemed  to  be  something  which  could 
be  brought  in  ships  and  wrapped  up  in  cloth- 
ing, and  was  evidently  communicable  from 
man  to  man.  Such  measures  of  stopping  the 
spread  of  the  disease  by  isolating  the  sick, 
and  such  general  regulation  of  the  diet  and 
habits  as  seemed  from  experience  best  adapted 
to  protect  the  well,  were  formulated  and 
practised.  But  the  lack  of  knowledge  as  to 
the  exact  nature  of  the  infective  agent  fre- 
quently rendered  futile  the  one  and  uncertain 
the  others. 

To-day  we  know  that  Asiatic  cholera  is 
caused  by  a  little  curved  bacillus,  which  on 


Asiatic  Cholera  in 

getting  into  the  intestinal  canal  of  human 
beings  multiplies  with  such  rapidity  that 
within  a  few  days  or  hours  the  body  may  be 
overwhelmed  with  the  poisonous  material 
which  it  eliminates  as  it  grows.  We  know 
that  in  certain  stages  of  the  disease  the  living 
germs  are  discharged  from  the  body  in  vast 
numbers,  and  that  if  moisture  be  present 
they  may  remain  alive  outside  of  the  body 
for  long  periods  and  may  even  multiply. 
They  can  thus  remain  alive  for  some  time  in 
water  and  on  the  moist  surfaces  of  vegetables 
and  fruits  and  clothing. 

There  is  no  good  reason  for  believing  that 
any  other  germ  or  organism  than  this  par- 
ticular curved  bacillus  ever  induces  Asiatic 
cholera,  or  that  the  disease  is  ever  caused  by 
anything  else.  The  only  known  way  in  which 
the  infective  agent  is  conveyed  from  man  to 
man  is  by  the  taking  into  the  intestinal  canal, 
either  by  water  or  food  or  in  some  other  way, 
some  of  the  cholera  bacilli  which  have  come 
directly  or  indirectly  from  some  human  victim 
of  the  disease. 

The  germs  may  remain  alive  for  a  long  time 


ii2         The  Story  of  the  Bacteria 

if  kept  moist,  and  so  the  disease  may  be  con- 
veyed for  long  distances  in  bundles  of  in- 
fected clothing.  A  few  hours  of  thorough 
drying,  or  steaming,  or  the  application  of 
suitable  disinfectants,  such  as  strong  carbolic 
acid  or  corrosive  sublimate,  readily  secures 
total  destruction  of  the  life  of  the  germs. 
1  In  Asiatic  cholera,  as  in  all  of  the  other 
bacterial  diseases  which  we  have  thus  far 
studied,  predisposition  of  the  individual  is  an 
important  factor  in  the  acquirement  of  the 
disease.  This  simply  means  that  there  are 
certain  conditions  of  the  body  cells  which 
render  them  less  able  to  resist  the  incursions 
of  foreign  organisms  like  the  bacteria,  or 
which  furnish  conditions  favorable  to  their 
growth  and  proliferation. 

We  have  seen  that  in  tuberculosis  this  pre- 
disposition to  the  disease,  whatever  its  exact 
nature  is,  may  be  in  a  certain  degree  heredi- 
tary. In  Asiatic  cholera,  a  disordered  con- 
dition of  the  digestion  appears  to  favor  the 
occurrence  of  an  attack  of  the  disease.  In 
typhoid  fever,  analogous  predisposing  fac- 
tors seem  to  determine  that  when  exposed  to 


Asiatic  Cholera  113 

the  same  risk  of  infection  one  individual  may 
be  attacked  with  the  disease  and  another  not. 
But  alike  in  all  these  forms  of  bacterial 
disease  the  particular  species  of  bacteria 
belonging  to  each  must  be  present,  predispo- 
sition or  no  predisposition,  or  the  disease 
cannot  occur. 

Typhoid  fever  and  cholera  are  often  called 
filth  diseases,  and  to  bad  food,  foul  air,  sewer 
gas,  and  overcrowding,  their  occurrence  has 
often  been  attributed.  This  is  in  a  sense 
true,  since  these  adverse  conditions  are  apt 
to  induce  a  state  of  the  body  which  renders 
it  less  resistent  than  it  should  naturally  be 
to  various  deleterious  agencies.  But  no  im- 
aginable degree  of  unsanitary  conditions  could 
ever  induce  tuberculosis,  or  typhoid  fever,  or 
Asiatic  cholera  without  the  presence  of  the 
particular  germ  which  causes  each.  None 
of  these  diseases  can  spring  up  among  any 
class  or  condition  of  people  without  the  in- 
troduction of  the  germ  from  outside. 

The  recently  acquired  knowledge  of  the 
cause  of  Asiatic  cholera  has  thus  far  aided 
but  little  in  the  treatment  of  persons  already 


ii4         The  Story  of  the  Bacteria 

its  victims.  On  the  other  hand,  knowing 
definitely,  as  we  now  do,  what  causes  the 
disease,  how  and  under  what  conditions  it 
spreads,  and  what  will  destroy  the  germs,  we 
are  to-day  in  a  condition,  wherever  sanitary 
and  proper  quarantine  regulations  are  effi- 
ciently carried  out,  to  largely  prevent  the  access 
of  the  disease  to  our  country,  to  stay  the 
progress  of  an  epidemic  at  its  very  outset, 
and  to  promptly  allay  the  panic  which  the 
advent  of  a  mysterious  and  deadly  scourge 
is  so  prone  to  incite. 


CHAPTER  XI 

PNEUMONIA,    INFLUENZA,    AND   COLDS 

Pneumonia 

PNEUMONIA  is  an  inflammation  of  the 
lungs,  and  is  usually  incited  by  bacteria. 
The  species  which  is  the  most  common  in- 
citant  of  the  disease  in  grown  people  is  called 
Pneumococcus.  But  in  children  and  some- 
times in  adults  the  pyogenic  bacteria,  which 
we  have  looked  at  in  a  former  chapter,  and 
other  forms  are  also  frequently  at  work. 

You  see  that  here  in  pneumonia  we  have 
a  disease  which,  unlike  tuberculosis  and 
typhoid,  may  be  induced  by  any  one  of 
various  forms  of  germs  and  not  infrequently 
several  forms  act  together. 

In  the  most  common  type  of  pneumonia 
in  adults  the  bacteria  almost  always  get 

"5 


n6        The  Story  of  the  Bacteria 

into  the  blood,  so  that  there  is  what  we  have 
learned  to  call  a  bacteriaemia  as  well  as  an 
inflammation  of  the  lungs.  In  the  lungs  a 
great  many  leucocytes  as  well  as  other  ma- 
terial accumulates  in  the  air  spaces  and  this 
sometimes  makes  the  patient  short  of  breath. 
The  pneumococcus  is  a 
very  minute  lance-shaped  or- 
ganism,  which  is  often  sur- 
rounded by  a  transparent 

FIG.  12.— THE  PNEU-  J 

MOCOCCUS  capsule  (Fig.  12).     It  can  be 

This   shows  the  artificially    cultivated,     but 

delicate  transparent  it   is   a  very   sensitive   and 

capsule  which  sur-  short-lived  thing,  easily  killed 

rounds  the  bacteria.  J 

by  drying,  by  sunlight,  and 
ordinary  disinfectants  such  as  carbolic  acid. 
It  is  present  in  the  mouth  and  nose  of  a 
considerable  proportion  of  healthy  persons 
to  whom  it  ordinarily  does  no  harm.  Just 
what  the  conditions  are  which  set  this  germ 
at  work  in  the  lungs,  we  do  not  know  very 
definitely.  Old  people  and  infants  are  par- 
ticularly susceptible.  Feeble,  overworked,  ill- 
nourished,  debilitated  folks,  and  those  who 
stay  in  very  dusty  places  are  also  liable  to 


Pneumonia,  Influenza,  and  Colds     117 

pneumonia.  It  is  most  frequent  in  the  late 
winter  and  the  spring  because  then  the  general 
resistance  of  the  body  has  been  commonly 
lowered  by  the  long  overstrain  and  confine- 
ment of  the  season's  work. 

Pneumonia  is  essentially  an  indoor  disease, 
or  if  it  occur  among  out-door  folks  this  is 
almost  always  because  they  have  been  to 
town  or  have  consorted  with  house  dwellers 
who  habitually  harbor  the  pneumococcus. 
Exposure  to  cold  and  wet,  contrary  to  the 
common  belief,  plays  but  an  insignificant 
part  in  predisposing  to  this  disease. 

In  the  United  States,  pneumonia  is  one  of 
the  most  frequent  and  serious  of  the  infectious 
maladies.  Over  ten  per  cent,  of  all  who  die 
are  victims  of  this  largely  preventable  disease. 

Through  unguarded  sneezing  and  coughing, 
by  the  uncared  for  sputum  of  those  who  are 
suffering  from  pneumonia,  the  pneumococcus 
may  be  distributed  in  virulent  form  to  those 
who  do  not  harbor  it. 

If  we  safeguard  ourselves  against  these  out- 
side sources  of  contamination  and  attend 
properly  to  the  toilet  of  the  mouth  and  keep 


n8         The  Story  of  the  Bacteria 

as  well  as  may  be  in  good  physical  condition, 
not  neglecting  colds  or  inflammations  of 
the  ear  or  eye,  which  are  themselves  often 
due  to  the  pneumococcus,  and  keep  out  of 
dusty  places,  we  shall  have  done  our  part  in 
turning  the  cold  shoulder  to  this  uncanny 
neighbor  to  which  we  are  so  often  unwittingly 
the  host. 

In  serious  pneumonia  there  is  evidence  of 
a  profound  internal  poisoning  of  the  body, 
doubtless  largely  due  to  the  great  number  of 
pneumococci  which  are  present  in  the  affected 
lung.  These  poisons  or  toxins  as  we  call  them, 
the  body  cells  strive  to  dispose  of  as  best  they 
may,  in  ways  which  we  shall  consider  in  a  later 
chapter.  For  this  purpose  the  body  cells 
must  have  plenty  of  oxygen.  That  means 
all  the  fresh  air  the  patient  can  use.  The 
modern  physician,  following  the  way  along 
which  Dr.  Northrup  has  so  skilfully  and 
persistently  led,  recognizes  this  supreme  need 
of  fresh  air  in  the  treatment  of  pneumonia, 
and  so  with  the  body  of  the  patient  properly 
protected,  keeps  the  windows  wide  open. 
This  arming  of  the  body  with  fresh  air  is 


Pneumonia,  Influenza,  and  Colds     119 

one  of  the  most  effective  of  the  modern  ways 
of  fighting  bacteria  and  their  poisons. 

Influenza 

It  is  popular  nowadays  for  both  doctors 
and  laymen  to  call  severe  colds  influenza 
or  "the  grip/'  But  genuine  contagious  in- 
fluenza, which  occasionally  sweeps  around 
the  world,  a  veritable  plague  out  of  the  Far 
East,  and  in  one  after  another  of  the  countries 
which  it  crosses  puts  a  large  share  of  the 
people  to  bed  with  all  sorts  of  miseries,  is 
apparently  incited  by  a  special  bacillus  which 
is  very  small  even  for  bacilli.  It  can  be  cul- 
tivated in  tubes  and  is  very  well  known 
nowadays  in  the  laboratory  as  well  as  at  the 
discouraged  bedside. 

The  Bacillus  influenzae  is,  however,  still 
somewhat  of  an  enigma,  because  it,  or  several 
organisms  quite  like  it,  are  found  in  a  good 
many  abnormal  conditions,  especially  in- 
volving the  respiratory  organs.  However, 
we  know  definitely  enough  that  the  influenza 
bacillus  is  transmitted  from  the  sick  to  the 


120        The  Story  of  the  Bacteria 

well  by  the  discharges  from  mouth  and  nose, 
especially  by  unguarded  spitting,  coughing, 
and  sneezing.  It  is  readily  killed  by  drying 
and  by  disinfectants,  and  does  not  ap- 
parently thrive  outside  the  bodies  of  human 
beings.  But  it  may  linger  alive  and  virulent 
for  a  long  time  in  the  mouth  and  nose  of 
convalescents  or  those  associated  with  pa- 
tients, and  so  it  is  carried  all  over  the  world 
when  once  the  virulent  strain  gets  started 
as  it  did  in  1889-91. 

The  safeguards  against  influenza  lie,  as  in 
so  many  of  the  infections,  in  care  for  the 
general  health,  proper  care  of  the  secretions, 
and  judicious  toilet  of  the  mouth.  The  doc- 
tor knows  best  what  to  do  when  you  have 
got  it,  and  it  is  well  to  call  him  in,  for  there 
is  much  misery  while  it  is  going  on  and  serious 
results  sometimes  if  you  are  indiscreet,  and  he 
can  almost  always  help  the  body  to  overcome 
or  outwit  the  unwelcome  intruders. 

Colds 

Of  all  the  infectious  diseases,  the  so-called 
"colds"  are  the  most  frequent.  We  have  all 


Pneumonia,  Influenza,  and  Colds     121 

had  them  and  all  know  how  unpleasant  they 
are,  and  how  apt  we  are  sooner  or  later  to 
recover  from  them.  What  we  do  not  so 
commonly  realize  is  that  if  they  are  neg- 
lected they  greatly  predispose  the  body  to 
much  more  serious  infective  maladies. 

Common  colds  are  incited  by  a  variety 
of  micro-organisms  among  the  more  common 
of  which  are  the  pneumococcus  and  strep- 
tococcus, and  bacilli  which  closely  resemble, 
if  they  are  not  identical  with,  a  mild  type  of 
the  influenza  germ.  Probably  several  other 
species  are  also  guilty,  but  conviction  waits 
upon  further  evidence.  Some  forms  of  colds 
are  distinctly  communicable,  and  run  through 
families  or  groups  of  closely  associated  persons. 

The  popular  impression,  crystallized  in  the 
name,  that  they  are  primarily  due  to  ex- 
posure to  cold  weather,  to  drafts,  to  fog  and 
wet,  is  largely  false.  All  these  things,  as 
well  as  indigestion,  overexertion,  or  anything 
else  which  lowers  the  body's  vigor  and  re- 
sistance, may  be  and  doubtless  are  con- 
tributory factors, — the  spark  which  lights 
the  powder.  But  without  the  germs  there 


122         The  Story  of  the  Bacteria 

would  be  no  "colds,"  as  certainly  as  without 
the  powder  there  would  be  no  explosion. 

People  who  really  live  out-of-doors  do  not 
often  have  colds.  When  they  come  to  town, 
or  get  into  closed  rooms  with  the  sneezing, 
coughing  urbanites,  who  live  and  move  and 
have  their  being  in  an  atmosphere  invisibly 
lurid  with  bacteria  fresh  from  infected  sources, 
then  the  outdoor  folks  catch,  not  the  cold, 
but  the  germ  which  does  it. 

Colds,  like  pneumonia  and  tuberculosis,  are 
indoor  diseases  and  savor  of  closed  rooms, 
foul  and  dusty  air,  crowded  assembly  places. 
The  vigorous  jubilant  home-comer  from  his 
summer  outing,  who  has  been  blown  and 
rained  upon,  who  has  spent  shivering  nights 
under  the  stars,  who  has  "cooled  off"  in  the 
wind  and  tramped  in  the  water,  who  has  pro- 
longed his  swim  till  he  was  blue,  with  never  a 
trace  of  ill,  gets  a  cold  a  week  after  he  comes 
back  to  town.  He  blames  the  open  window 
by  which  he  sat  to  relieve  himself  of  the 
stuffiness  of  his  city  home.  But  he  forgets 
the  ill  cleaned  dusty  car  with  its  scores  of 
germ-dispensing  occupants  in  which  he  trav- 


Pneumonia,  Influenza,  and  Colds    -123 

elled  home,  or  the  filthy  theatre,  never  in- 
telligently cleaned  at  all  most  likely,  in  which 
he  whiled  away  an  evening  just  to  get  in 
touch  with  the  spirit  of  the  town.  These, 
and  not  the  fresh  air  at  his  window,  gave  him 
the  real  inspirers  of  his  cold. 

Keep  the  body  vigorous  by  good  food  and 
water,  by  plenty  of  work  and  play,  but  don't 
overdo  either.  Adopt  the  old  Chinese  pro- 
verb "Do  nothing  too  much. "  Get  the  fresh- 
air  habit.  Open  the  windows  in  the  bedroom 
and  in  all  rooms.  Keep  down  the  dust. 
Get  every  possible  hour  out-of-doors.  Keep 
the  skin  clean  and  the  body  as  lightly  clothed 
as  is  comfortable.  Woollen  underwear  does 
not  prevent  colds.  A  proper  toilet  of  the 
mouth  is  not  to  be  neglected.  Finally,  like 
a  good  citizen,  join  the  forces  now  engaged 
in  securing  cleaner  air  in  all  assembly  places, 
in  cars,  shops,  hotels,  stores,  theatres,  courts, 
churches,  as  well  as  at  home.  Frown  upon 
the  folks  who  sneeze  and  cough  and  spit  in 
fashion  worse  than  brutish.  Then  if  you  do 
get  colds  now  and  then,  as  you  will, — for 
sanitary  decency  is  not  to  be  won  in  a 


124         The  Story  of  the  Bacteria 

day, — you  will  have  a  fair  chance  for  a  light 
infection. 

If  people  with  acute  colds  could  and  would 
sequester  themselves  for  a  few  days  and  rest 
while  the  body  overcomes  the  invaders,  it 
would  be  much  better  for  them  and  an  active 
source  of  infection  for  others  would  be 
removed. 


CHAPTER  XII 

DIPHTHERIA  AND  TETANUS 

Diphtheria 

P\IPHTHERIA  is  a  disease  most  frequent 
1— J  in  children,  in  which  a  membrane  is 
apt  to  form  in  the  air  passages,  which  may 
make  breathing  difficult  or  impossible.  There 
are  also  symptoms  of  serious  general  disorder, 
as  if  the  body  were  profoundly  poisoned. 

The  disease  is  incited  always  by  a  pecul- 
iar, often  club  shaped  bacterium  called  the 
Bacillus  diphtherias  (Fig.  13).  It  is  killed  by 
boiling  for  a  minute  or  by  disinfectants,  but 
may  live  for  months  in  the  air.  This  bacillus 
is  present  in  enormous  numbers  in  the  mem- 
brane, and  sometimes  gains  entrance  to  the 
body.  But  the  chief  damage  to  the  victim 
of  diphtheria  is  a  powerful  poison  which  the 

125 


126        The  Story  of  the  Bacteria 

germ  manufactures  as  it  grows,  and  which  is 
absorbed  into  the  blood.  This  disease  is 
therefore  a  toxczmia. 

The  bacillus  of  diphtheria  is  readily  cul- 
tivated in  beef  tea  or  on  the  usual  solid  bac- 
terial foods,  where  it  produces  the  same  poison 
that  is  formed  in  the  disease 
process.  We  shall  return  to 
this  diphtheria  poison  or 
toxin  a  little  later,  when  we 
look  at  the  various  ways  in 

FIG.      13.  —  BACIL-  . 

LUS  DIPHTHERIA  which  the  body  protects  it- 
self against  pathogenic  bac- 
teria, and  the  ways  which  modern  science  has 
discovered  to  help  it. 

While  diphtheria  is  a  very  serious  disease, 
the  use  of  antitoxin,  the  nature  of  which  we 
shall  consider  farther  on,  has  robbed  it  of  its 
greatest  terrors  and  very  much  reduced  its 
frequency.  It  is  rare  in  animals. 

The  diphtheria  bacilli  are  often  conveyed 
from  the  sick  to  the  well  by  the  material 
discharged  from  the  mouth  and  nose,  either 
directly,  or  by  eating  utensils,  towels,  etc. 
Furthermore  the  bacilli  often  remain  for 


Diphtheria  and  Tetanus  127 

many  weeks  or  months  alive  in  the  mouths  and 
throats  of  those  who  have  recovered  from  the 
disease.  They  are  also  frequently  found  in  the 
mouths  of  well  persons  exposed  to  the  disease, 
as  well  as  of  those  who  are  not  known  to  have 
associated  with  diphtheria  patients. 

This  is  one  of  many  reasons  why  we  should 
try  to  avoid  exchanging  mouth  secretions 
with  others  by  avoiding  the  use  of  common 
drinking  vessels  or  towels,  and  by  more 
seemly  sneezing  and  coughing;  why  children 
should  not  suck  pencils  and  pass  them  on, 
or  indulge  the  friendly  impulse  to  share  the 
handkerchief  or  chewing  gum.  This  is  why 
adults,  as  well  as  children,  should  not  in- 
salivate the  leaves  of  books  and  papers  as  they 
turn  them  over  by  wetting  the  fingers  in  the 
mouth.  Finally  the  story  of  the  diphtheria 
bacillus  as  of  the  pneumococcus  and  the  tu- 
bercle germ  suggests  the  propriety  of  less 
catholicity  than  is  usual  as  to  whom,  and 
more  circumspection  as  to  how,  we  kiss. 

Tetanus  or  Lockjaw 
Tetanus  is  induced  by  a  remarkable  bacillus 


128        The  Story  of  the  Bacteria 

common  in  the  cultivated  soil,  in  street  dust, 
and  in  the  droppings  of  the  horse  and  other 
herbivorous  animals.  The  bacilli  when  grow- 
ing in  the  body  produce  an  intense  poison, 
which  acts  especially  through  and  upon  the 
nervous  system.  Thus  powerful  spasms  of  the 

muscles  are  produced, 
and  when  the  muscles 
of  the  jaw  are  affected, 
they  become  rigid, 
hence  the  common 

FIG.    14. — TETANUS   BACILLI 

Showing  spores  name  lockjaw. 

The  bacillus  of  te- 
tanus does  not  grow  well  in  contact  with 
oxygen,  and  when  it  finds  itself  under  un- 
favorable conditions  for  growth,  it  forms 
a  spore  which  is  very  resistent  to  external 
influences,  and  drying,  heat,  disinfectants, 
etc.,  which  ordinarily  kill  bacteria.  Then 
it  stands  pat  and  waits  for  something  bet- 
ter to  turn  up.  The  bacteriologist,  how- 
ever, can  cultivate  it  by  shutting  oxygen  out 
of  his  tubes  and  plates  and  consulting  its 
peculiar  tastes  in  other  ways.  The  bacillus 
when  forming  spores  is  shaped  something 


Diphtheria  and  Tetanus  129 

like  a  tennis  racquet,  with  the  shiny  spore  in 
the  larger  end  (Fig.  14). 

The  horse  and  some  other  animals  only 
occasionally  develop  tetanus,  though  one 
great  source  of  the  bacillus  is  horse  manure. 

Humans  get  tetanus  by  dirty  wounds, 
usually  bruised  or  punctured.  Pure  cultures 
or  spores  of  the  germ  are  not  apt  to  induce 
tetanus  in  wounds,  but  when  other  bacteria 
or  dirt  are  introduced  into  a  wound  with  the 
tetanus  bacilli  these  are  apt  to  grow.  Thus 
it  is  that  although  spores  of  the  bacillus  of 
tetanus  are  very  widely  distributed  in  nature, 
the  disease  is  not  common,  because  it  is  only 
in  punctured  or  lacerated  wounds,  in  which 
spores  and  dirt  are  lodged  together,  that  the 
proper  conditions  exist  for  the  growth  of  this 
finicky  citizen.  This  is  why  those  who  care 
for  horses,  those  who  handle  manure,  and  the 
boy  who  celebrates  the  "Fourth"  with  a 
toy  pistol  are  the  most  frequent  victims  of 
lockjaw.  There  are  some  regions  in  which  the 
soil  contains  a  great  many  spores,  so  that 
tetanus  frequently  follows  even  slight  punc- 
tured wounds. 


130         The  Story  of  the  Bacteria 

Careful  cleaning  and  disinfection  of  dirty 
wounds,  especially  those  which  are  lacerated 
or  punctured,  is  the  proper  safeguard  against 
this  common  bacillus. 

It  is  finally  noteworthy  that  while  inmost 
of  the  bacterial  diseases  the  infectious  agent 
is  transmitted  more  or  less  directly  from  the 
sick  to  the  well,  and  is  usually  more  virulent 
the  more  direct  and  recent  the  conveyance 
is,  we  have  in  tetanus  almost  the  only  ex- 
ample of  pathogenic  bacteria  widely  and 
persistently  contaminating  the  soil.  But  it 
is  so  particular  in  its  habits  that  it  is  only  now 
and  then  that  it  falls  afoul  of  human  beings. 

It  has  been  possible  through  experiments 
on  animals  to  prepare  an  effective  antitoxin 
for  the  tetanus  poison.  Its  usefulness  is, 
however,  considerably  limited  by  the  fact  that 
the  symptoms  of  tetanus  do  not  develop  until 
the  germ  toxin  has  gained  a  powerful  hold 
upon  the  nervous  system,  when  it  may  be  too 
late  to  neutralize  it  with  the  artificial  anti- 
body. 


CHAPTER  XIII 

A  ROUND-UP  OF  UNDESIRABLES 

Meningitis 

THERE  is  another  ball-shaped  microbe  or 
coccus  closely  related  to  the  pneumo- 
coccus  which  is  responsible  for  a  very  serious 
communicable  disease  prone  to  affect  children 
by  an  inflammation  of  the  covering  membrane 
of  the  brain  and  spinal  cord.  As  this  mem- 
brane is  called  the  meninges,  the  disease  is 
named  cerebro-spinal  meningitis,  and  the 
microbe  is  called  the  meningococcus.  It  is 
found  sometimes  in  the  nose  and  throat  of 
its  victims  and  their  associates.  It  has  been 
cultivated  and  carefully  studied.  Dr.  Flexner 
at  the  Rockefeller  Institute  for  Medical  Re- 
search in  New  York  has  secured  from  horses 
treated  with  cultures  of  the  meningococcus 

131 


132         The  Story  of  the  Bacteria 

a  curative  serum  which  has  been  used  all 
over  the  world  and  has  saved  many  lives. 

Gonorrhcea 

There  is  still  another  of  this  uncanny  family 
of  cocci  called  the  gonococcus,  which  is  the 
inspirer  of  great  misery  and  leads  to  many 
deaths. 

It  is  the  nemesis  of  the  licentious  and 
debauchers  of  the  racial  instinct,  and  in  their 
retribution  their  many  innocent  victims  share. 
It  is  the  cause  of  a  large  part  of  the  blindness 
of  infancy. 

Syphilis 

Syphilis  is  a  disease  which  is  primarily  almost 
always  dependent  upon  an  infringement  of 
the  laws  governing  the  racial  instinct,  and  is 
usually  the  penalty  of  depraved  associations. 
Retribution  to  the  offender  often  lasts  through 
life,  and  the  innocent  are  often  hopelessly 
involved. 

The  inciting  agent  of  syphilis  is  a  minute 
spiral  bacterium  whose  life  history  is  not  yet 


A  Round-up  of  Undesirables      133 

known  since  it  has  not  been  artificially  culti- 
vated and  so  cannot  be  studied  free  from 
complicating  conditions. 

The  infective  organism  is  naturally  limited 
to  the  human  race,  though  monkeys  can  be 
experimentally  infected. 

Except  for  the  few  instances  in  which  by 
accident  the  infective  agent  has  been  conveyed, 
it  is  seldom  known  to  be  a  source  of  danger  to 
those  of  honorable  life,  except  through  inti- 
mate association  with  its  victims. 

The  Plague 

The  plague,  or  "black  death"  as  they  called 
it  when  it  ravaged  Europe  in  the  middle  ages, 
has  a  very  ancient  and  sinister  history.  You 
may  read  about  it  in  the  pages  of  Bocaccio 
or  Defoe.  It  had  largely  disappeared  from 
Europe  for  a  century  and  a  half.  But  in  the 
latter  part  of  1900  it  started  afresh  in  China 
and  India,  and  gradually  worked  its  way  into 
the  Americas.  It  has  never  fairly  gained  a 
foothold  in  the  United  States,  thanks  to 
effective  quarantine,  except  in  San  Francisco, 


134         The  Story  of  the  Bacteria 

where  for  a  long  time  there  have  been  scatter- 
ing cases. 

The  plague  bacillus  is  short  and  plump  and 
grows  very  easily  in  cultures  and  in  such 
characteristic  ways  that  it  is  readily  recognized. 
It  is  easily  killed  by  drying,  sunlight,  and 
disinfectants. 

<.  In  one  form  of  the  disease  pneumonia  is  a 
prominent  feature,  and  then  the  germ  may  be 
transmitted  from  the  sick  to  the  well  by  the 
discharges  from  mouth  and  nose. 

But  in  severe  epidemics  of  plague  the  num- 
ber of  persons  affected  is  so  large  that  some 
other  mode  of  transmission  of  the  bacillus 
than  by  personal  contact  has  to  be  assumed. 
And  here  we  come  upon  a  keen  reminder  that 
some  of  the  lower  animals  which  we  cordially 
despise,  as  is  the  case  with  the  house-fly,  are 
significant  factors  in  the  discomfort  which 
man  derives  from  inheriting  the  earth. 

It  has  been  found  that  in  plague  epidemics 
rats  share  with  man  in  the  predilections  of 
the  plague  bacillus,  having  an  enormous 
mortality  of  their  own.  The  evidence  indeed 
is  strong  that  man  derives  his  plague  bacilli 


A  Round-up  of  Undesirables      135 

from  the  rat.  But  the  question  is  how? 
Rats  do  not  often  bite  men  or  closely  consort 
with  them,  nor  do  they  notably  contaminate 
human  food.  But  rats  have  fleas  and  when 
these  bite  infected  rats  they  borrow  the 
bacilli  with  the  blood  and  if  then  they  bite 
a  man  the  bacilli  may  be  directly  introduced 
into  his  system. 

Much  study  has  shown  that,  in  fact,  in 
countries  and  regions  where  plague  prevails 
the  rat  and  the  flea  are  potent  factors  in 
transmission. 

In  California  where  plague  has  been  lurking 
for  some  years,  some  of  the  ground  squirrels 
have  become  infected  with  plague  bacilli  and 
while  this  is  not  yet  of  threatening-  import- 
ance, it  is  disquieting  that  the  infective  agent 
has  not  long  since  been  completely  destroyed. 

Smallpox  and  its  Relatives 

It  is  very  interesting  that  with  all  our  study 
of  micro-organisms  and  long  familiarity  with 
these  diseases,  smallpox,  measles,  and  scar- 
let fever  should  still  remain  riddles  among  the 
common  infections.  These  diseases  are  all 


136         The  Story  of  the  Bacteria 

characterized  by  an  eruption  on  the  skin. 
The  old  Greeks  knew  them  and  called  it  a 
"flowering  out,"  and  so  we  call  the  lot  "the 
exanthemata."  We  do  not  know  what  incites 
them.  The  search  for  bacteria  has  thus  far 
failed. 

It  has  been  conjectured  that  minute  ani- 
mals— protozoa — may  be  to  blame.  Some 
morning  we  shall  probably  learn  in  the  papers 
that  a  tired-eyed  worker  in  the  laboratory 
has  found  the  clue,  and  we  shall  wonder  that 
we  did  n't  always  know  it. 

But  though  we  do  not  yet  know  what  in- 
cites them,  we  have  for  .one — smallpox — so 
efficient  a  preventive  in  vaccination,  that  it 
has  largely  lost  its  terrors  in  civilized  and 
intelligent  communities,  and  has  ceased  to 
figure  largely  in  health  statistics.  This 
happy  state  has  been  secured  through  the 
wisdom  and  vigilance  of  health  authorities, 
which  must  be  ceaselessly  maintained. 

Hydrophobia  or  Rabies 

Here  is  another  infectious  disease  usually 
acquired  through  animals,  in  this  country, 


A  Round-up  of  Undesirables      137 

usually  the  dog.  The  nature  of  the  infective 
agent  is  unknown.  It  is  apparently  not 
bacterial.  Learned  folks  guess  it  to  be  a 
protozoan. 

But  nevertheless  here,  as  in  smallpox,  a 
most  effective  method  of  prevention  has  been 
devised  by  Pasteur,  so  that  one  bitten  by  a 
mad  dog  has  the  best  of  chances  to  escape  the 
disease  if  he  will  but  promptly  apply  for 
treatment  to  the  appropriate  laboratories 
maintained  by  health  departments  and  others. 
The  nature  of  the  preventive  treatment  in 
hydrophobia  is  considered  briefly  elsewhere  in 
this  book. 

Malaria 

This  wearisome  malady  is  not  induced  by 
bacteria  and  so  is  only  smuggled  in  here  to 
round  out  the  census  of  common  infections. 
It  is  due  to  a  tiny  animal,  a  protozoan,  which 
is  conveyed  from  the  sick  to  the  well  through 
the  bite  of  a  particular  species  of  mosquito 
called  Anopheles.  The  germ  itself  is  named 
Plasmodium  malar  ice.  It  takes  the  two  of 


138         The  Story  of  the  Bacteria 

them  to  get  the  better  of  their  big  brother, 
man. 

But  man  has  more  brains  and  has  found  out 
that  the  weakest  link  in  the  chain  of  his 
inoculation  is  the  mosquito,  and  when  he 
drains  the  marshes  in  which  most  of  the  little 
buzzing  brethren  breed,  and  screens  his 
windows  against  the  plebeian  minority  to 
whom  stale  water  in  old  bottles,  tin  cans, 
water  butts,  and  puddles  is  birthplace,  his 
" shakes"  disappear  and  he  becomes  a  worth- 
while citizen  again. 

Yellow  Fever 

This  is  a  tropical  disease  but  may  flourish 
in  temperate  climates  in  summer.  It  ceases 
when  the  frost  comes.  It  is  certainly  infec- 
tious, it  does  not  affect  the  lower  animals, 
and  we  do  not  know  what  living  thing  incites 
it.  It  was  formerly  supposed  to  be  contagious 
and  the  infective  agent  carried  in  the  clothing. 
But  through  a  series  of  brilliant  recent  re- 
searches, it  is  now  known  that  the  yellow- 
fever  germ  is  carried  from  the  sick  to  the  well 


A  Round-up  of  Undesirables      139 

by  a  particular  species  of  mosquito  called 
Stegomyia,  which  sucks  blood  and  the  parasite 
from  the  patient  and  transfers  it  to  persons 
whom  he  may  later  visit. 

There  is  a  very  fascinating  story  in  the  dis- 
covery of  the  yellow-fever  mosquito  and  his 
significance  to  man,  but  we  cannot  tell  it  here. 
We  may  only  say  that  when  they  screened 
the  mosquito  away  from  the  fever  patients 
so  that  he  could  not  get  infected  blood,  they 
stamped  out  yellow  fever  in  Havana,  and 
can  control  it  anywhere  by  keeping  tab  on 
Stegomyia. 

It  is  sadly  aggravating  to  the  scientific 
folk  to  realize  that  though  they  can  get  an 
infected  mosquito  which  they  know  contains 
the  deadly  infective  parasite  somewhere  in 
his  interior,  no  cultivating,  no  microscoping 
or  any  other  scrutiny  has  succeeeded  in 
recognizing  the  living  thing  which  must  be 
right  under  their  eyes.  It  probably  is  a 
protozoan,  and  it  is  demonstrably  so  small 
that  the  most  powerful  microscopes  fail  to 
reveal  it.  It  seems  to  be  one  of  a  very  baf- 
fling group  of  living  beings  causing  disease, 


140         The  Story  of  the  Bacteria 

which  are  called  ultra-microscopic,  and  which 
no  man  has  really  distinctly  seen  except  in 
masses. 

Whooping-cough  and  Mumps  belong  among 
the  milder  infective  maladies,  but  their  incit- 
ing agents  have  not  yet  been  clearly  identified. 

There  are  many  other  diseases  of  men  and 
animals  incited  by  bacteria  which  are  of  much 
less  importance  than  those  which  we  have 
glanced  at  in  our  hurried  survey.  But  the 
limits  of  this  little  book  do  not  permit  us  to 
dwell  upon  them. 


CHAPTER  XIV 

SAFEGUARDS    OF    THE    BODY  AGAINST    DISEASE 

WHEN  we  try  to  learn  more  about  the 
human  body  than  we  can  by  ob- 
serving its  form  and  structure  and  the  various 
obvious  things  which  it  can  do,  we  are  led 
back  to  the  time  when  that  mysterious  potency 
called  life  stole  in  upon  the  earth  in  the  pri- 
meval silences.  And  we  are  obliged  to  trace 
the  changes  which,  through  stress  of  circum- 
stance, have  slowly  shaped,  out  of  a  single 
cell,  the  various  cell  communities  and  their 
marvellous  correlated  activities  which  make 
the  human  being  of  to-day. 

All  these  changes  have  been  brought  about 
by  the  adaptation  of  form  and  activity  to  new 
environments.  And  we  can  discern  here  and 

there  through  all  the  various  cells  and  organs, 

141 


142         The  Story  of  the  Bacteria 

and  all  the  things  they  do,  the  marks  of 
earlier  stages  of  development. 

The  uncouth  ancestral  being,  which  by  and 
by  was  to  be  moulded  into  man,  once  had 
need  of  more  bowel  space  than  he  now  re- 
quires. But  when  this  became  unnecessary 
a  segment  of  it  wasted  away,  leaving  a  weazen 
remnant  which  we  call  the  appendix,  and 
which  gives  some  folks  a  good  deal  of  bother 
now  and  then.  There  was  a  weak  spot  in  the 
lower  abdomen  once  when  man's  progenitor 
went  on  all  fours.  This  interested  him  not  at 
all  then.  But  when  his  descendant  got  along 
in  his  development  so  as  to  stand  up  on  his 
hind  legs,  the  pressure  of  the  bowels  on  this 
weak  spot  was  much  increased,  and  so  some 
people  find  a  knuckle  of  intestine  pressing 
out  in  what  we  call  a  rupture  or  hernia.  Thus 
we  might  go  on  a  good  while  with  these  marks 
of  forgotten  histories  cropping  out  occasion- 
ally in  the  last  of  the  long  ancestral  line. 

But  what  especially  concerns  us  now,  is 
the  more  subtle  marks  of  evolution  in  the 
intimate  performances  of  the  body  cells. 
Whatever  capacities  they  now  possess  and 


Safeguards  against  Disease       143 

use  so  cleverly  for  the  welfare  of  the  whole 
community,  they  have  acquired,  as  we  have 
said,  through  long  ages  of  adaptation  to  new 
conditions.  By  adaptation  we  mean  making 
the  best  of  it.  Now  this  power  -of.  adaptation 
the  body  cells  possess  to-day,  subject  to  the 
work  and  strain  of  ordinary  life.  The  body 
cells  can  adapt  themselves  to  new  kinds  of 
food  and  to  more  or  less  of  it,  to  changes  of 
temperature,  to  new  forms  of  work,  and  so  on. 
Life  is,  in  fact,  a  constant  adjustment  to 
varying  conditions.  If  these  new  conditions 
become  too  extreme,  the  efforts  of  adaptation 
are  exaggerated,  the  capacity  is  overstrained, 
the  rhythm  of  correlated  activities  is  broken, 
and  this  is  disease.  But  the  pull  of  the 
ancestral  experiences,  which  we  call  heredity, 
is  ever  back  to  the  balanced  activities  called 
health.  This  pull  of  the  ancestral  experiences 
is  what  the  doctors  have  in  mind  when  they 
abandon  the  Saxon  tongue  and  speak  of  the 
vis  medicatrix  natures, — the  healing  power  of 
nature. 

Now,  all  this  is  important  in  studying  the 
safeguards  of  the  body  against  disease,  be- 


144         The  Story  of  the  Bacteria 

cause  the  biggest  safeguard  which  the  body 
has  against  disease  is  this  capacity  of  the 
cells  to  adapt  themselves,  within  reasonable 
limits,  to  new  and  often  adverse  conditions. 
This  is  combined  with  their  habit,  acquired 
through  several  millions  of  years  of  inherited 
experience,  of  getting  back  into  the  old  ways 
again  as  soon  as  possible.  These  are  the 
powers  which  the  doctor  must  work  with  and 
not  against,  with  his  regimen  and  diet,  with 
his  fresh  air  and  sunshine,  with  his  counsel 
and  cheer,  as  well  as  with  his  less  impor- 
tant offerings  of  drugs.  These  body  cells 
tend  to  get  back  at  their  tasks  again  after 
the  adventures  which  circumstances  force 
upon  them,  because  their  ancestors,  all  the 
way  up  the  line,  did  so  and  survived,  weav- 
ing their  experiences  into  the  vitals  of  their 
descendants;  while  collateral  branches  which 
did  n't  do  it,  perished.  Some  folks  call  this 
the  principle  of  the  survival  of  the  fittest. 

Another  of  the  body's  most  potent  safe- 
guards is  its  power  to  dispose  of  poisonous 
substances,  which  are  developed  within  it, 
or  get  in  from  outside.  With  our  food  we 


Safeguards  against  Disease       145 

take  in  a  very  nondescript  mess  of  chemical 
substances,  and  incidentally  a  good  many  mill- 
ions a  day  of  bacteria.  The  intestinal  processes 
spell  death  to  myriads  of  bacteria  with  which 
our  uncooked  foods  are  mingled.  The  chemi- 
cal substances  are  pulled  to  pieces  by  the  diges- 
tive juices,  and  a  part  of  this  refined  food-stuff 
gets  into  the  blood.  The  residue  is  regularly 
and  safely  disposed  of.  The  part  which  gets 
into  the  blood  is  robbed  of  some  of  its  harm- 
ful ingredients  in  the  liver  or  elsewhere.  The 
rest  of  the  internal  waste  gets  out  through 
the  kidneys  or  lungs  or  by  the  sweat-glands 
of  the  skin.  The  selected  elements  of  the 
food  finally  come  to  the  body  cells,  which 
proceed  to  tear  it  further  to  pieces,  use  what 
they  want,  and  again  set  free  another  set  of 
residues,  some  of  them  very  poisonous  if 
retained  in  the  body,  but  in  health  got  safely 
rid  of  again  by  the  kidneys,  lungs,  and  skin. 
Thus  it  is  that  while  in  the  ordinary  course 
of  life  we  are  constantly  beset  with  varied 
and  subtle  poisons,  the  mechanism  of  the 
body  is  so  nicely  adjusted  that  we  are  saved 
from  harm  by  our  cells,  some  of  which  feed 


146        The  Story  of  the  Bacteria 

and  thrive  upon  poisons  which  without  these 
curious  proclivities  would  inevitably  damage 
or  destroy  them,  and  us.  This  power  of  the 
body  cells  and  organs  to  destroy  and  dispose 
of  internal  waste  and  poisonous  material  is, 
then,  the  second  of  our  great  protective 
agencies  against  disease. 

The  bacterial  poisons  are  disposed  of  through 
the  very  agencies  which  are  constantly  guard- 
ing our  bodies  from  harm  by  the  home-made 
poisons  which  we  ourselves  elaborate.  These 
agencies  consist  largely  of  new  chemical 
unions  into  which  the  poisons  are  forced  to 
enter,  thus  losing  their  identity  and  their 
harmfulness. 

Another  important  safeguard  of  the  body 
is  certain  tiny  cells,  the  most  significant  of 
which  we  have  glanced  at  in  an  earlier  chapter, 
the  leucocytes  or  white-cells  of  the  blood  (see 
Plate  XI.,  i).  Although  the  body  can  main- 
tain its  form  and  structure  and  go  on  doing 
its  work,  often  beyond  the  orthodox  threescore 
years  and  ten,  it  is  in  fact  constantly  changing. 
New  cells  are  forming  and  old  ones  are  dying, 
some  are  damaged  and  must  be  speedily 


? 


'*•' 


PLATE  XI. — LEUCOCYTES  AND  PHAGOCYTES 

I. — Shows  a  leucocyte  or  white  blood  cell  with  its  irreg- 
ular shaped  nucleus  and  the  translucent  delicate  cell-body. 

2.— Shows  a  leucocyte  which  has  taken  into  its  body 
particles  of  soot,  breathed  in  by  its  owner  from  dusty  air. 
This  leucocyte  is  thus,  for  the  time  being,  a  phagocyte. 

3. — This  phagocyte  has  taken  into  its  body  several  bac- 
teria— micrococci  —  a  few  of  which  have  been  partially  de- 
stroyed. 

4- — This  is  one  of  the  larger  phagocytes  of  the  body 
which  has  in  its  interior,  portions  of  other  smaller  dead  cells. 
These  are  here  undergoing  disintegration. 


Safeguards  against  Disease       147 

replaced,  and  there  is  everywhere  more  or  less 
wear  and  tear.  Now  in  all  these  changes 
there  is  first  and  last  a  good  deal  of  dead  stuff 
to  be  disposed  of. 

|:.;  While  other  cells  here  and  there  lend  a  hand 
in  this  scavenger  work,  it  is  the  leucocytes 
which  bear  the  brunt  of  it,  and  it  is  in  truth 
a  busy  life  they  lead.  Fragments  of  dead 
cells  or  tissue  (Plate  XI.,  4),  particles  of  foreign 
material  which  accidentally  may  have  got  into 
the  tissues,  they  engulf  (Plate  XI.,  2).  Some 
of  these  they  sooner  or  later  digest  and  thus 
dispose  of,  or  if  this  be  not  feasible,  they  carry 
them  off  to  safe  places  of  deposit  within  the 
body.  The  regular  leucocyte  dumping  grounds 
of  our  busy  interiors  are  the  so-called  lymph- 
glands  or  lymph-nodes,  of  which  we  have 
many  snugly  stored  in  appropriate  places— 
in  the  neck,  the  armpit,  the  groin,  at  the  root 
of  the  lungs,  and  within  the  abdomen. 

Here  various  types  of  scavenger  cells  fore- 
gather and  work  over  their  never  ending 
supply  of  booty  from  the  farthest  recesses  of 
the  body.  If  through  the  subtle  chemistry 
of  their  own  juices  they  can  convert  the  stuff 


148         The  Story  of  the  Bacteria 

into  soluble  or  nutrient  or  harmless  form  they 
do  so.  If  it  is  too  intractible  for  that,  it  is 
stowed  away  on  the  spot  in  dormant  cells  or 
in  the  crannies  of  the  node,  where  it  is  less 
harmful  than  in  the  thoroughfares  or  special 
workshops  of  the  great  community. 

These  leucocytes  are  par  excellence  the 
wandering  cells  of  the  body — for  not  only 
do  they  share  with  the  red  blood  cells  in  the 
passive  transportation,  which  the  blood  and 
lymph  currents  afford,  but  unlike  the  red 
cells  they  have  noteworthy  locomotive 
capacities  of  their  own;  so  that  they  can 
crawl  about  in  the  minute  crannies  of  the 
tissues  where  the  tiniest  fragment  of  a  useless 
particle  is  to  be  found.  A  few  other  cells  share 
in  the  locomotive  powers  of  the  leucocytes. 

The  leucocytes  and  other  cells  which  take 
foreign  particles  into  their  interiors  have 
received  a  special  name — Phagocytes — which 
means  "devouring  cells."  This  is  only  a  sort 
of  trade  name,  suggesting  one  of  many  occu- 
pations of  the  white  blood  cells,  and  when 
other  cells  share  this  special  task  they,  too, 
become  for  the  moment  phagocytes.  Thus 


Safeguards  against  Disease       149 

the  leucocytes  do  not  cease  to  be  leucocytes 
when  they  become  phagocytes,  any  more 
than  a  son  of  Erin  ceases  to  be  an  Irishman 
when  he  becomes  a  plumber. 

The  leucocytes,  as  well  as  some  other  body 
cells,  have  the  further  useful  capacity  of 
secreting  and  under  certain  conditions  setting 
free,  such  chemical  substances  in  solution 
as  dissolve  refractory  tissues,  dead  bone,  for 
example,  and  so  clear  the  ground  for  new 
growth. 

Thus  far  we  have  been  considering  harmful 
stuff  in  the  body,  such  as  poisons  and  dead 
particles,  and  the  ways  in  which  the  body 
protects  itself  against  them.  Now  let  us 
look  at  some  more  striking  aliens,  themselves 
alive,  which  often  intrude  upon  the  balanced 
life  of  the  healthy  man. 

The  presence  of  bacteria  in  the  body  is  of 
varying  significance,  depending  upon  where 
they  are  and  what  their  pedigree.  The  healthy 
skin  keeps  out  most  of  them.  The  ever 
swinging  cilia  in  the  windpipe  sweeps  them 
out  in  hosts.  In  the  mouth  and  nose  many 
are  destroyed,  but  many  lead  here  a  placid, 


150         The  Story  of  the  Bacteria 

harmless  life.  Along  the  digestive  canal  they 
swarm.  But  these  are  mostly  harmless,  some 
even  lending  a  hand,  perhaps,  in  reducing  our 
complex  foods  to  simple  forms.  The  tonsils 
are  rather  weak  points  in  the  body  armor, 
for  through  them  several  objectionable  germs, 
among  them  the  tubercle  bacillus,  sometimes 
enter. 

When  bacteria  get  into  the  real  interior — 
for  the  lungs  and  bowels  we  may  wisely 
remember,  are  only  infoldings  from  the  ex- 
terior— when  they  get  into  the  very  tissue 
itself,  and  into  the  blood,  even  then  nothing 
very  startling  happens,  as  a  rule.  The  power 
of  the  leucocytes  and  other  cells  to  take  up 
dead  stuff  comes  in  handy  here,  for  when  the 
average  bacterium  is  encountered  in  the  homes 
of  the  leucocytes,  it  is  either  engulfed  forth- 
with or  poisoned  first  and  swallowed  after- 
wards (Plate  XI.,  3). 

It  is  only  now  and  then  with  the  very  few 
of  the  thousands  of  species  of  bacteria  which 
are  co-inhabitors  of  the  earth  with  us,  that 
difficulties  arise. 

There  are  doubtless  a  good  many  interesting 


Safeguards  against  Disease       151 

stories  in  the  relationship  of  bacteria  to  man 
if  we  could  only  wander  back  along  the  ways 
of  evolution.  For  we  have  all  grown  up 
together  through  the  ages,  we  and  the  bacteria, 
each  adapting  himself  to  the  requirements 
of  the  other.  When  this  mutual  adjustment 
is  secured,  we  do  each  other  no  harm.  Our 
cells  and  the  bacterial  cells  then  work  hand  in 
hand.  Infectious  diseases  are  the  efforts  of 
adaptation  to  conditions  which  have  not  yet 
become  usual.  That  the  invading  micro- 
organisms in  infection  also  have  their  hour 
of  storm  and  stress,  as  they  encounter  the 
damaging  forces  which  our  cells  command, 
is  proven  every  time  we  get  well. 

Bacteria,  as  we  have  seen,  make  trouble 
in  the  body  very  little  by  their  mere  physical 
presence,  but  by  poisons  which  some  of  them 
form  and  set  free  as  they  live  and  grow,  or 
which  they  store  up  to  be  liberated  when  they 
die  and  break  to  pieces.  So  when  in  our 
cherished  interiors  the  poison-breeding  bac- 
terial cell  encounters  our  well  bred  body  cell, 
it  is  a  battle  in  which  the  weapons  are  poisons. 
For  some  of  the  fluids  and  digestive  juices 


OF   THE 
IIMIVFRSITY 


152         The  Story  of  the  Bacteria 

which  our  own  cells  elaborate  are  just  as  much 
poisons  for  the  bacteria  as  is  their  venomous 
stuff  for  us. 

In  the  end  it  is  the  old  story  of  the  survival 
of  the  fittest.  When  these  two  types  of  cell 
meet,  each  trying  to  get  a  living  in  its  own 
way  wherever  it  has  been  stranded  by  the 
wave  of  circumstance,  a  new  environment  is 
established  for  the  body  cell  and  for  the 
bacterium.  And  what  we  dramatize  as  a 
battle,  is  really  only  the  attempt  of  each  to 
adapt  itself  to  the  new  conditions  furnished 
by  the  other;  so  that  each  can  go  on  and  get 
a  living.  The  one  which  adapts  itself  most 
readily  and  completely  and  quickly  wins,  by 
survival. 

We  please  our  fancy  sometimes,  by  making 
heroes  of  the  leucocytes,  dashing  at  the  in- 
truders in  their  hereditary  bailiwicks,  regardless 
of  the  risks  which  they  so  hardily  incur.  Let 
us  not  indulge  in  too  much  of  this,  lest  haply 
we  too  be  found  among  the  nature  fakirs. 
For,  in  fact,  they  are  impotent  pieces  of  the 
game  played  by  physical  and  chemical  forces, 
and  they  have  to  set  about  the  battle  willy- 


Safeguards  against  Disease          153 

nilly,  just  as  much  as  the  magnetized  needle 
has  to  swing  to  the  north,  quite  without 
concern  whether  the  ship  does  or  does  not  go 
upon  the  rocks. 

The  thing  which  we  want  to  glean  from  the 
rehearsal  of  this  cell  contest  is,  that  in  both 
animal  cell  and  bacterial  cell  the  capacities 
of  ordinary  life,  in  this  emergency,  are  set 
vigorously  at  work  to  meet  the  requirements 
of  a  new  situation,  and  upon  the  way  they  meet 
it  depends  their  fate.  But  while  the  two 
kinds  of  cell  may  sway  and  modify  a  little 
their  every -day  functions  in  their  own  pro- 
tection, they  no  more  forge  new  weapons, 
than  would  a  stone-mason  who  should  rap  an 
imminent  foot-pad  over  the  head  with  his 
hammer. 

When  these  doughty  cells  succumb  to  the 
bacterial  poisons  which  they  encounter,  they 
are  picked  up  as  dead  stuff  by  other  forms 
of  cells  (Plate  XL,  4),  and  with  the  dead  in- 
vading hosts  are  decently  disposed  of. 

So  at  last  we  see  that  the  body  protects 
itself  against  bacteria  and  their  poisons  by 
the  use  of  the  same  agencies  which  it  has  made 


154         The  Story  of  the  Bacteria 

effective  through  ages  of  experience  in  keeping 
its  interior  fresh  and  wholesome  and  clear 
of  its  own  refuse  and  the  intruding  flotsam 
and  jetsam  of  a  dusty  world. 

But  through  all  these  marvellous  adaptive 
processes  by  which  the  body  maintains  its 
balance  among  the  pitfalls  of  a  sorely  jostled 
life,  is  felt  the  steady  pull  of  heredity  back 
to  the  line  of  health.  This  we  fondly  drama- 
tize as  the  beneficent  touch  of  good  old 
Mother  Nature.  But  it  really  is  the  ultimate 
impress  upon  the  cell  republic  and  its  citizens, 
every  one,  of  the  unrecorded  adaptations  to 
the  conditions  of  each  hour,  whether  for 
good  or  ill,  since  the  first  living  cell  appeared, 
surprised  and  lonesome,  upon  a  hitherto 
inanimate  earth. 


CHAPTER  XV 

HOW  SCIENCE  HELPS  THE  BODY  IN  INFECTION 

WE  have  seen  how,  through  many  ex- 
cellent arrangements  in  our  cells,  we 
manage  to  keep  alive  in  spite  of  a  great  many 
threatening  conditions.  In  fact,  good  Mother 
Nature — let  us  again  risk  the  phrase — makes 
a  pretty  good  job  of  it,  in  a  large  proportion 
of  cases,  whether  we  know  how  she  does  it 
or  not.  But  there  are  a  great  many  people 
on  the  earth  and  a  great  many,  for  them, 
malignant  bacteria.  The  body  machines  of 
many  folks  are  woefully  abused  or  sadly 
handicapped  in  the  race  of  life.  So  in  the 
long  run  Nature  scores  many  failures.  If 
you  want  to  get  an  idea  how  many  there 
are  of  these,  look  at  the  death-rate  from 
bacterial  diseases  in  any  district  of  the  United 
States  in  a  single  year,  and  you  will  see  that 

155 


156         The  Story  of  the  Bacteria 

she  seems  to  be  overworked  or  lacks  resources. 
In  New  York  City,  for  example,  in  1907  there 
were  between  8,000  and  9,000  deaths  from 
tuberculosis  of  the  lungs;  nearly  700  from 
typhoid  fever,  about  as  many  from  scarlatina; 
over  i, 600  from  diphtheria,  and  more  than 
600  from  cerebro-spinal  meningitis.  This 
looks  as  if  Nature  needed  help,  as  in  truth 
she  does. 

Now  let  us  see  how  science  is  trying  to  lend 
a  hand. 

It  is  clear,  in  a  general  way,  how  the  body 
protects  itself  against  harmful  bacteria  by 
its  power  of  neutralizing  their  poisons,  by 
destroying  them  with  its  cells,  and  by  its 
inherent  tendency  to  get  well,  whatever  hap- 
pens. But  science  must  know  more  than  this. 
If  it  is  going  to  help  to  neutralize  poisons  it 
must  know  more  of  the  processes  which  the 
body  uses  for  this  purpose.  If  it  is  to  rein- 
force the  efforts  of  the  cells  in  killing  and 
destroying  bacteria,  it  should  get  behind  the 
scenes  and  learn,  if  possible,  how  this  is  done 
in  the  single-handed  conflicts  which  mark 
each  hour  of  life. 


How  Science  Helps  the  Body     15? 

Animal  species  differ  in  their  capacity  to 
protect  themselves  against  germs  and  their 
poisons.  Many  bacteria  deadly  to  some  of 
the  lower  animals  are  harmless  to  man,  and 
vice  versa.  This  freedom  from  danger  of 
special  microbic  invasion  is  called  immunity. 
Since  it  is  born  with  the  individual,  it  is  called 
natural  or  hereditary  immunity.  Some  of  the 
factors  concerned  in  this  we  have  already 
considered. 

But  there  is  another  phase  of  immunity 
which  we  must  look  at  a  little  more  closely. 
People  who  recover  from  some  of  the  infectious 
diseases,  such  as  small-pox,  measles,  scarlet 
fever,  and  in  a  less  degree  from  typhoid  fever, 
diphtheria,  and  others,  are  protected  for  a 
longer  or  shorter  time  from  a  subsequent 
attack.  Such  people  enjoy,  while  it  lasts, 
what  is  very  properly  called  acquired  immunity, 
an  immunity  acquired  through  an  experience 
of  the  disease  itself.  Now  what  is  it  in  the 
bodies  of  these  people  who  have  successfully 
weathered  an  infectious  disease  which  pro- 
tects them  from  another  attack?  If  we  could 
answer  this  question  we  should  evidently  be 


158         The  Story  of  the  Bacteria 

well  on  the  way  toward  understanding  the 
nature  of  acquired  immunity.  They  must 
be  in  some  way  different  from  their  fellows 
and  must  have  either  acquired  some  new 
qualities  which  they  did  not  possess  before 
their  disease  adventure,  or  old  protective 
agencies  must  have  been  reinforced. 

How  light  has  been  thrown,  little  by  little, 
on  this  important  subject  by  the  busy  self- 
sacrificing  workers,  both  in  the  laboratory 
and  at  the  bedside,  makes  an  interesting 
story  which  we  cannot  now  stop  to  tell.  But 
the  fact  is,  that  when  certain  poisons,  espe- 
cially those  formed  by  bacteria,  get  into  the 
body,  some  of  the  body  cells  proceed  forth- 
with to  make  and  set  free  chemical  substances 
which  unite  with  the  poisons,  changing  their 
character  and  making  them  harmless. 
Through  this  action  of  his  cells,  the  recovering 
victim  of  an  infection  destroys  the  poisons  as 
they  are  made.  The  bacteria  which  make 
the  poisons  are  thus  robbed  of  their  chief 
significance  and  do  not  particularly  concern 
the  patient  any  further.  So  he  gets  well. 
But  something  more  may  happen.  His  cells, 


How  Science  Helps  the  Body     159 

which  were  stimulated  in  the  poison-emerg- 
ency to  produce  neutralizing  stuff,  speedily 
fall  into  the  habit  of  making  it,  and  go  on 
doing  so,  often  for  a  long  time,  after  the 
master  of  the  cells  has  recovered  and  after 
his  actual  necessity  for  it  has  ceased. 

Now  at  last  we  see  why  he  cannot  soon 
suffer  from  the  same  disease  again.  His 
body  contains  a  good  deal  of  the  protective, 
poison-neutralizing  agent,  and  his  cells  go  on 
making  more  for  a  time,  so  that  he  goes  about 
poison-proof.  By  and  by,  however,  the  old 
hereditary  pull  back  to  the  usual  routine  is 
felt,  the  emergency  cell  activity  wanes,  the 
excess  of  protective  material  disappears,  and 
the  acquired  immunity  passes  away.  So 
the  hero  of  this  dramatic  story  of  disease 
takes  his  place  again  among  ordinary  mortals. 

Now  in  scientific  speech  certain  poisons  are 
known  as  toxins.  And  so  this  cell-made 
emergency  stuff,  which  robs  the  toxins  of 
their  power,  is  known  as  antitoxin.  Anti- 
toxins are  effective  only  against  the  special 
poisons  which  inspire  the  cells  to  their  pro- 
duction— that  is,  they  are  specific.  An  anti- 


160         The  Story  of  the  Bacteria 

toxin  for  the  diphtheria  bacillus  poison,  for 
example,  would  not  at  all  protect  against  the 
tetanus  poison,  or  vice  versa. 

As  soon  as  research  had  gone  thus  far  into 
the  problem  of  immunity,  the  thought  of  the 
lonesome  worker  in  the  laboratory  turned,  as 
it  is  wont  to  do,  with  every  new  outlook, 
toward  the  needs  of  suffering  mortals.  If 
in  the  body  of  an  infected  animal,  as  is  the 
case  in  man,  this  protective  antitoxin  may 
be  formed  in  excess — so  ran  the  thought  of 
the  investigator — might  it  not  be  possible 
to  treat  animals  with  special  forms  of  bacteria 
or  their  poisons,  and  when  their  cells  have  been 
educated  to  the  overproduction  of  the  specific 
antitoxin,  draw  off  some  of  the  blood  con- 
taining it,  and  by  introducing  this  into  the 
body  of  a  human  victim  of  the  disease,  save 
him  from  impending  death  by  poison?  This 
significant  and  humane  suggestion  has  been 
worked  out  into  a  practical  system.  And 
now  the  world  over  are  laboratories  from  which 
are  derived  life-saving  antitoxins  of  various 
kinds. 

Among  these  the  first  to  be  secured  and  the 


How  Science  Helps  the  Body     161 

most  important  is  the  antitoxin  of  diphtheria. 
This  is  prepared  from  the  horse.  It  is  not 
necessary  to  cause  the  horse  to  endure 
diphtheria,  as  we  know  it,  at  all.  For  if 
the  poison  which  the  diphtheria  bacillus 
sets  free,  when  it  is  grown  in  beef -tea  cultures 
in  the  laboratory,  with  all  the  germs  filtered 
off,  be  put  into  the  horse,  his  cells  get  to  work, 
just  as  ours  do  when  we  have  the  disease, 
diphtheria,  and  just  as  his  would  if  the  bacilli 
were  allowed  to  grow  in  his  body.  Presently 
antitoxin  begins  to  mingle  with  his  blood. 

The  horse  lends  himself  readily  at  first  to 
small,  then  to  increasing  doses  of  the  potent 
diphtheria  poison.  He  becomes  readily  im- 
mune and  he  is  so  big  that  he  furnishes  a  large 
amount  of  blood  without  apparent  inconven- 
ience. When  the  animal  is  poison  proof,  no 
longer  showing  any  ill  effects  to  doses  of  the 
toxin  so  large  that  if  given  at  first  they  would 
have  been  inevitably  fatal,  he  is  bled  from 
a  large  vein  in  the  neck.  The  blood  is  set 
in  a  cool  place  and  clots,  clear  fluid,  the  serum, 
separating  from  the  rest.  This  yellowish 
clear  serum  contains  the  antitoxin. 


1 62         The  Story  of  the  Bacteria 

All  these  operations  are  most  carefully  done 
so  that  the  antitoxic  serum  is  pure  and  clean, 
and  it  is  introduced  beneath  the  skin  of  the 
patient  with  a  small  syringe  made  for  the 
purpose. 

This  is  a  hasty  outline  of  the  story  of 
diphtheria-antitoxin-making.  You  see,  the 
cells  of  the  horse  make  antitoxin  to  protect 
themselves  and  him  from  the  toxin  which  is 
artificially  introduced  by  his  skilled  attendant. 
This  antitoxin  will  neutralize  diphtheria  toxin 
wherever  it  encounters  it,  whether  in  a  test- 
tube  or  in  the  body  of  a  poisoned  child  facing 
imminent  death.  The  child  is  struggling  to 
make  what  antitoxin  he  can  for  himself.  If 
his  cells  can  make  it  in  plenty  and  make  it 
soon  enough,  he  may  recover  unaided.  But 
the  antitoxic  serum  of  the  horse  is  just  as 
good;  it  works  quickly,  it  raises  high  the 
chances  of  a  successful  issue. 

Since  the  introduction  of  diphtheria  anti- 
toxin the  mortality  from  diphtheria  has 
been  reduced  quite  75  per  cent.  Just  what 
this  means  in  the  saving  of  life  and  in  the 
relief  of  suffering,  only  those  can  realize  who 


How  Science  Helps  the  Body     163 

saw  diphtheria  in  the  old  days  and  have  read 
the  sinister  story  of  the  early  statistics. 

But  the  antitoxin  of  diphtheria  is  also  of 
the  greatest  value  in  the  prevention  of  the 
disease  among  those  who  have  been  exposed 
to  infection  in  families,  schools,  and  elsewhere. 

The  immunity  which  the  child  secures 
through  the  diphtheria  which  it  survives,  is 
won  at  great  cost  and  risk.  It  is  called  active 
immunity.  Through  it  the  body  cells  have 
adapted  themselves  to  a  new  unfavorable 
environment.  On  the  other  hand,  the  im- 
munity conferred  upon  the  child  by  the  anti- 
toxin which  the  horse  manufactures,  is  called 
passive  immunity.  The  effect  is  immediate 
and  quite  under  control.  But  the  protection 
is  short-lived  and  the  body  soon  eliminates 
the  foreign  agent  from  its  blood  and  tissues. 
The  antitoxin  does  not  destroy  the  diphtheria 
bacilli.  The  body  cells  take  care  of  them  as 
soon  as  the  blight  of  the  poison  is  effaced. 

In  similar  fashion  valuable  curative  anti- 
toxins are  made  for  cerebro-spinal  meningitis 
and  for  tetanus,  and,  though  less  successful, 
for  a  few  other  infections. 


164         The  Story  of  the  Bacteria 

Of  course  the  eager  workers  in  the  labora- 
tories have  tried  to  get  antitoxins  for  many 
other  of  the  bacterial  diseases.  But  somehow 
the  method  did  not  seem  to  work  so  well  in  all. 
There  are  many  obvious  reasons  why  this 
should  be,  but  they  are  too  complex  to  con- 
sider here.  There  is  little  doubt  that  as 
research  goes  on  still  further  discoveries  will 
be  made  of  effective  antitoxins. 

In  the  meantime,  however,  the  student  of 
bacterial  diseases  has  turned  to  other  phases 
of  the  protective  mechanism.  Active  im- 
munity can  be  secured  in  other  ways  than  by 
the  weathering  of  an  infection.  Thus  it  has 
been  found  that  if  a  mass  of  disease-inducing 
bacteria,  from  an  artificial  culture,  be  killed 
by  heat  and  portions  of  these  be  introduced 
into  the  body,  its  cells  gradually  adapt  them- 
selves to  the  poisons  which  the  dead  bacteria 
contain,  so  that  the  body  is  in  a  measure 
protected  from  an  attack  of  the  disease  of 
which  they  are  the  regular  incitants. 

Thus  with  typhoid  fever,  Asiatic  cholera, 
and  plague,  important  practical  results  have 
been  secured.  The  persons  thus  forearmed 


How  Science  Helps  the  Body     165 

are  found  to  be  much  less  liable  to  acquire 
the  disease  in  prevailing  epidemics.  These 
results  are  due  to  the  fact  that  some  patho- 
genic bacteria,  instead  of  setting  toxic  sub- 
stances free  as  they  grow,  store  them  up  in 
their  bodies.  Later  when  these  are  killed  by 
heat  and  degenerate,  the  toxins  are  set  free, 
inciting  the  body  cells  to  their  protective 
activities. 

We  have  thus  far  been  considering  the 
ways  in  which  the  body  may  be  helped  to 
free  itself  from  the  presence  and  action  of 
poisons  produced  by  disease-inciting  germs. 
Now  what  can  be  done  to  help  the  body  to 
kill  and  destroy  the  bacteria  themselves  and 
so  stop  the  poison  fountains  at  their  sources? 

It  has  long  been  known  that  the  body 
fluids  kill  bacteria  in  enormous  numbers,  even 
those  of  serious  infectious  maladies,  and  we 
have  much  knowledge  of  the  chemical  agencies 
by  which  this  is  accomplished. 

It  has  been  shown  that  there  are  two  groups 
of  substances  in  the  body  fluids,  one  at  least 
of  which  may  be  increased  in  artificial  im- 
munization, which,  when  acting  together, 


1 66         The  Story  of  the  Bacteria 

have  the  power  to  induce  disintegration  and 
destruction  of  bacteria.  This  action  is  called 
lytic,  which  means  dissolving.  Thus  we  now 
speak  of  the  destructive  action  of  the  body 
fluids  on  the  bacteria  as  bacteriolytic.  There 
is  reason  to  believe  that  one  of  the  most 
important  agencies  of  the  body  in  protecting 
itsjslf  against  invasive  micro-organisms  is  this 
bacteriolytic  power  of  its  fluids.  This  power 
is  the  same  as  the  body  has  always  made  use 
of  in  disposing  of  its  own  dead  or  useless 
cells,  but  it  is  here  diverted  to  new  ends  to 
meet  an  emergency. 

While  there  appears  to  be  in  this  new 
knowledge  of  bacteriolysis  the  brightest  prom- 
ise of  future  practical  usefulness  in  the 
control  of  infection,  we  need  to  know  more 
about  the  cells  which  make  these  protective 
substances  and  the  conditions  of  their  forma- 
tion before  we  can  effectively  lend  a  hand.  • 

But  it  has  been  found  that  by  introducing 
into  the  body,  in  certain  infections,  some  of  the 
killed  bacteria  which  incite  them,  the  body 
cells  are  stimulated  to  produce  substances 
which  so  alter  such  of  these  bacteria  as  are 


How  Science  Helps  the  Body     167 

already  at  their  destructive  work,  that  they 
become  an  easier  prey  for  the  ever  vigilant 
phagocytes  (Fig.  15).  The  bodies  of  the  killed 


FIG.    15. — PHAGOCYTES    AND    VACCINES 

This  cut  shows  two  phagocytes  from  animals  infected 
with  staphylococcus  pyogenes — the  common  pus-forming 
bacterium.  The  animal  from  which  the  cell  at  the  left  was 
taken  was  untreated.  The  animal  from  which  the  right  hand 
cell  was  taken  had  been  treated  with  "  vaccine"  consisting  of 
a  culture  of  these  organisms  killed  by  heat.  Many  more 
bacteria  have  been  taken  up  by  the  phagocyte  of  the  vac- 
cine treated  animal. 


bacteria  thus  used  are  called  vaccines  and  the 
substances  produced  by  the  body  cells  under 
their  influence  are  known  as  opsonins.  This 
name  is  derived  from  a  Latin  word  which  means 
"I  prepare  food  for."  The  manufacture  of 


1 68         The  Story  of  the  Bacteria 

opsonins  by  the  body  cells  under  the  inspira- 
tion of  vaccines  has  been  most  effective  in 
infections  by  the  pyogenic  cocci.  Though 
called  by  the  same  name,  these  new  "  vaccines  " 
have  nothing  to  do  with  the  vaccine  lymph 
which  is  used  to  prevent  small-pox. 

It  is  generally  believed  to-day  that  most  of 
the  substances  in  the  body  fluids  which  kill 
and  destroy  bacteria  are  furnished  in  part  at 
least  by  the  leucocytes.  So  these  doughty 
defenders  of  the  cell  republic  reach  marauding 
bacteria,  not  only  when  alive  by  personally 
swallowing  them,  but  by  setting  free  germ- 
killing  stuff  when  they  have  succumbed. 

Based  upon  this  knowledge  of  the  effective 
action  of  the  leucocytes  in  setting  free  pro- 
tective stuff,  Dr.  Hiss  has  proposed  to  secure 
leucocytes  in  quantity  from  the  lower  animals 
— the  rabbit  for  example, — and  to  introduce 
an  extract  of  these  into  the  bodies  of  persons 
suffering  from  acute  infections,  thus  rein- 
forcing their  capacity  for  resistance. 

This  method  of  treatment  is  still  under 
investigation.  But  the  reports  of  those  who 
have  applied  it  in  a  variety  of  human  in- 


How  Science  Helps  the  Body     169 

fections  seem  to  indicate  that  the  extracts  of 
alien  leucocytes  used  in  this  way  may  be  of 
great  value. 

The  incitants  of  small-pox  and  hydrophobia 
are  as  yet  unknown,  though  they  are  prob- 
ably not  bacteria.  But  we  have  methods  of 
preventive  inoculation  in  both  of  these  serious 
diseases  which  are  remarkably  effective. 

These  methods  both  depend  upon  the 
gradual  adaptation  of  the  body  cells  to  an 
infectious  agent.  At  first  material  of  slight 
virulence  is  used;  then  that  which  is  more 
potent.  Thus  presently  the  body  cells,  with- 
out the  acquirement  of  the  disease  by  the 
individual,  have  become  so  fully  adapted  to 
the  new  conditions,  that  the  body  is  protected 
from  the  disease  altogether. 

In  small-pox  the  virus  of  diminished  viru- 
lence is  secured  by  passing  it  through  the 
body  of  an  insusceptible  animal,  the  calf. 
Then,  while  it  does  not  induce  small-pox 
in  man,  it  protects  man  from  it. 

In  hydrophobia  the  unknown  living  in- 
fective agent,  which  is  present  in  the  nervous 
system  of  rabic  animals,  through  the  method  of 


170         The  Story  of  the  Bacteria 

Pasteur,  is  treated  by  drying  the  nerve  tissue 
in  the  air,  in  which  process  its  virulence 
steadily  diminishes.  Thus  it  is  possible  to 
get  'material  of  all  grades  of  strength.  So 
that  if  a  person  bitten  by  a  mad  dog  be  injected 
at  first  with  a  long-dried  material,  then  day 
after  day  with  that  which  has  been  dried  for 
a  shorter  time,  at  length  with  no  symptoms 
whatsoever  to  indicate  that  his  cells  have 
been  responding  to  a  powerful  infective  agent, 
he  has  acquired  complete  immunity  or  pro- 
tection from  the  disease,  which  has  not  been 
permitted  to  develop. 

The  mortality  from  hydrophobia  before  the 
day  of  preventive  inoculation  was  about  six- 
teen per  cent.  Through  this  treatment  it  has 
been  reduced  to  about  two  tenths  of  one  per 
cent. 

In  the  early  days  of  our  knowledge  of 
bacteria,  the  highest  hope  was  cherished  that 
it  would  soon  be  possible  to  destroy  bacteria 
in  the  body  by  disinfectants.  But  this  hope 
soon  faded,  for  it  was  found  that  any  such  sub- 
stance strong  enough  to  be  effective  would  kill 
the  body  cells  as  soon  as  it  would  the  bacteria. 


How  Science  Helps  the  Body     171 

But  there  is  one  infective  disease — malaria, 
not  induced  by  bacteria,  but  by  micro- 
organisms belonging  among  the  protozoa,  in 
which  the  early  dream  is  realized.  For  in 
most  cases  quinine  suffices  to  destroy  the 
organism  without  damaging  the  man.  Thus 
by  quinine  and  mosquito  screens  and  drain- 
ing the  swamps,  this  pest  of  many  coun- 
tries and  neighborhoods  may  be  effectively 
suppressed. 

We  have  thus  learned  that  there  is  an 
immunity  to  infection  which  faces,  species, 
and  individuals  naturally  enjoy  or  may  acquire 
by  a  successfully  encountered  attack  of  an 
infectious  disease.  We  have  seen  that  the 
body  cells  possess  a  marvellous  power  of 
adapting  themselves  to  new  adverse  condi- 
tions, by  the  use,  to  new  ends,  of  capacities 
by  which  the  usual  life  is  carried  on.  So 
when  one  recovered  from  diphtheria  or  typhoid 
fever  is  for  a  time  immune,  we  know  that  this 
marks  an  adaptation  of  his  cells  to  a  new 
environment,  evanescent  it  is  true,  but  analo- 
gous with  those  adjustments  by  which  in  the 
long  processes  of  evolution  new  traits  were 


172         The  Story  of  the  Bacteria 

fostered  as  plants  and  animals  slowly  rose  to 
higher  types. 

But  beyond  this  we  have  found  out  that  we 
can  secure  an  artificial  cell  adaptation  by 
proxy  in  the  horse,  and  through  his  cells, 
educated  for  the  occasion,  secure  the  precious 
juices  which  not  only  can  confer  immunity 
upon  the  well,  but  can  save  those  already 
stricken.  In  these  and  many  other  ways 
which  we  have  but  glanced  at  in  passing, 
we  can  reinforce  to-day  the  subtle  safeguards 
of  the  body  against  the  minute  incitors  of 
infection. 

If  we  compare  our  knowledge  of  infectious 
diseases  to-day  with  that  which  was  current 
twenty-five  years  ago,  it  is  evident  that  an 
advance  has  taken  place  which  is  fairly 
revolutionary.  Then  we  did  not  even  know 
what  caused  most  of  the  infections.  The 
efforts  to  cure  them  were  uncertain  and  in- 
effective, and  preventive  measures  were  largely 
futile.  To-day  we  know  what  the  causes  of 
most  of  these  diseases  are,  how  the  recupera- 
tive forces  of  the  body  meet  them,  in  many 
instances  what  we  can  do  to  help  these  forces, 


How  Science  Helps  the  Body     173 

and  finally  how  these  scourges  of  mankind 
can  be  controlled  by  a  little  honest  and  in- 
telligent cleanliness. 

Now  step  by  step  as  this  knowlege  has 
grown,  it  has  been  necessary  to  use  the  lower 
animals  in  studying  the  action  of  these  new- 
found micro-organisms,  and  the  ways  to  prevent 
their  ravages.  These  animal  experiments  are 
always  most  carefully  performed,  anaesthetics 
being  used  whenever  necessary,  by  the  hu- 
mane and  self-sacrificing  devotees  to  the 
advancement  of  knowledge.  Without  the  free 
and  untrammelled  use  of  the  lower  animals 
for  experimental  purposes,  children  would 
still  be  suffering  and  dying  by  thousands 
from  diphtheria  each  day,  the  world  over,  and 
the  doctors  would  be  helpless  to  save  them  or 
largely  stop  their  sufferings.  The  pitiful  victims 
of  cerebro-spinal  meningitis  would  still  face 
a  hopeless  future.  We  should  be  back  in  the 
old  age  of  helplessness  towards  most  of  the 
infectious  maladies. 

It  is  well  for  us  all  to  realize  this,  because  a 
number  of  persons,  a  part  of  whom  are  igno- 
rant but  well-meaning,  a  part  ignorant  and 


174         The  Story  of  the  Bacteria 

malicious,  are  stirring  about  and  endeavoring 
to  interfere  by  legislation  with  the  advance- 
ment of  science  through  that  research  which 
involves  the  use  of  certain  of  the  lower 
animals. 

It  is  one  of  the  duties  which  good  citizenship 
lays  upon  the  informed  and  the  honest,  to 
see  to  it  that  the  crusade  of  short-sighted 
ignorance  and  falsehood,  which  its  devotees 
name  anti-vivisection,  shall  not  be  permitted 
to  stay  the  progress  and  cloud  the  outlooks 
of  beneficent  research. 


CHAPTER  XVI 

THE   COMMON    SOURCES    OF    BACTERIAL 
INFECTION 

AS  we  glance  back  over  the  ground  which 
we  have  traversed  together,  we  see 
that  the  most  common  bacterial  diseases 
which  in  this  country  we  are  apt  to  come  in 
contact  with,  so  far  as  they  are  definitely 
known  to  us,  are  tuberculosis,  typhoid  fever, 
diphtheria,  influenza,  pneumonia,  and  the 
wound  diseases  or  blood  poisoning. 

We  have  seen  that  in  most  of  these  diseases 
the  infective  agent  is  liable  to  spread  from  one 
individual  to  another,  because  it  is  not  de- 
stroyed by  disinfectants,  or  in  some  other 
way,  as  soon  as  possible  after  it  is  discharged 
from  the  diseased  person. 

We  have  seen  that  the  most  common  ways 
in  which  the  virulent  bacteria  are  spread  are 
by  personal  contact  or  by  the  food  we  eat, 

175 


176         The  Story  of  the  Bacteria 

the  air  we  breathe,  and  the  water  we  drink. 
If  any  of  these  necessities  of  life  contain 
the  living  germs  of  these  diseases,  there 
is  a  liability  of  the  infection  of  healthy  or 
predisposed  individuals. 

The  liabilty  to  acquire  these  diseases  is 
always  increased  in  direct  proportion  to  the 
crowding  together  of  the  sick  and  the  well 
under  unsanitary  conditions  in  large  communi- 
ties. This  is  not  because  filth  and  dirt  are  in 
themselves  infectious,  but  because  pathogenic 
bacteria  are  liable  to  become  mingled  with  the 
rest.  In  other  words,  there  is  a  simply  filthy 
filth,  and  there  is  a  pathogenic  filth,  and  the 
two  are  very  apt  to  go  together. 

No  gas,  however  foul,  no  accumulation  of 
dirt,  no  degree  of  malnutrition  or  misery  or 
overcrowding  can  induce  an  infectious  disease. 
It  is  always  and  everywhere  some  particular 
form  of  disease-producing  germ  which  causes 
the  trouble.  The  other  influences  bear  largely 
upon  the  chances  of  incurring  the  disease,  and 
often  determine  the  severity  of  its  course  or 
its  fatal  ending,  but  they  alone  cannot  cause  it. 

It  is  not  the  great  and  sweeping  epidemics, 


Sources  of  Bacterial  Infection      177 

dramatic  and  frightful  as  they  are,  which 
carry  off  prematurely  the  largest  number  of 
people;  but  it  is  the  bacterial  diseases  which 
we  have  constantly  with  us,  and  to  which 
we  have  become  so  accustomed  that  we  do 
not  usually  realize  their  vast  importance,  and 
against  which  systematic  and  persistent  cru- 
sades on  the  part  of  the  health  authorities  are 
only  occasionally  and  fitfully  undertaken. 

Civilized  communities  have  ceased  to  fear 
Asiatic  cholera  very  much,  because  we  have 
learned  that  it  is  easily  suppressed  by  proper 
sanitation.  The  traditional  ravages  of  the 
plague  are  possible  only  among  the  filthy  in 
person  and  surroundings.  Small-pox  we  do 
not  now  seriously  dread,  because  immunity 
can  be  secured  by  a  scratch  upon  the  skin. 
Diphtheria  and  cerebro-spinal  meningitis  have 
largely  lost  their  terrors  since  the  discovery  of 
the  life-saving  antitoxins.  Hydrophobia  is 
fully  within  our  control. 

But  how  is  it  with  some  of  the  less  dramatic 
germ  diseases  which  we  have  always  with  us, 
although  we  have  known  for  many  years  how 
they  can  be  largely  prevented? 


1 78         The  Story  of  the  Bacteria 

Malaria  ravages  large  districts,  because  we 
do  not  drain  the  puddles  and  will  not  harden 
our  hearts  against  the  mosquito. 

Typhoid  fever  claims  its  victims  singly 
and  in  wholesale — more  than  thirty  thousand 
die  every  year  in  the  United  States — chiefly 
because  we  are  not  yet  ready  to  see  that  our 
sewage  is  disposed  of  elsewhere  than  in  our 
drinking  waters. 

Tuberculosis,  the  king  of  the  revels  in  this 
dance  of  death,  ends  a  lingering  illness  in 
fully  one  hundred  and  fifty  thousand  persons 
annually  in  this  country  alone.  And  these 
multitudes  perish  prematurely  because  we 
do  not  insist  upon  the  most  obvious  require- 
ments of  personal  hygiene  and  the  simplest 
details  of  public  and  private  sanitation. 

In  fact,  our  science  is  far  ahead  of  our  prac- 
tice, and  it  now  rests  largely  with  the  people  and 
the  health  officials  whom  they  select  to  guard 
their  interests  to  say  whether  or  not  in  the 
next  decade  we  shall  enter  into  our  birthright. 

It  is  not  difficult  to  suggest  broadly  the 
things  which  must  be  done  if  we  are  to  profit 
as  we  may  by  the  promise  of  preventive  medi- 


Sources  of  Bacterial  Infection      179 

cine.  Honest  hygiene  must  be  taught  in 
schools  and  colleges.  Public-health  officers 
must  know  more  about  sanitation  than  about 
politics,  and  there  must  be  educational  in- 
stitutions where  their  special  duties  can  be 
learned.  An  enlightened  public  sentiment 
must  sustain  them  in  their  efforts  to  promote 
the  general  welfare,  even  though  the  individual 
may  now  and  then  be  inconvenienced. 

But  when  efficiency  shall  have  been  secured 
in  the  public-health  administration,  a  large 
responsibility  will  still  rest  upon  the  citizen. 

He  can  get  clean  food,  pure  water,  and  un- 
polluted air  by  asking  for  them  and  insisting 
that  he  have  them.  But  he  must  insist,  and 
he  must  be  vigilant. 

The  danger  of  infection  with  disease-pro- 
ducing bacteria  which  we  may  encounter  in 
the  ordinary  paths  of  life  lurk,  as  we  have 
seen,  for  the  most  part,  either  in  food,  or  air, 
or  water.  Let  us  now  look  at  these  sources 
of  danger  a  little  more  closely. 

Food  Infection 
\Milk.     This  is  such  an  excellent  food  for 


i8o        The  Story  of  the  Bacteria 

bacteria  that  though  practically  germ-free 
when  it  comes  from  the  cow,  before  it  reaches 
the  consumer  it  may,  if  not  kept  cool,  contain 
millions  of  germs  in  a  single  spoonful. 

It  has  been  found  that  milk  which  contains 
a  great  many  bacteria,  though  these  may  not 
be  of  a  kind  which  ordinarily  induce  disease, 
in  infants  and  young  children  may  cause  serious 
even  fatal  digestive  disturbances.  But  well- 
known  disease-inducing  bacteria  often  get 
into  milk.  Tubercle  bacilli  may  come  from 
the  tuberculous  cow.  Typhoid  bacilli  may 
get  into  the  milk  in  careless  handling  di- 
rectly or  indirectly  from  typhoid-fever  cases 
or  from  "typhoid  carriers,"  or  by  the  use  of 
sewage-polluted  water  in  washing  the  cans; 
or  flies  in  their  wanderings  may  contaminate 
it.  Similarly,  the  bacteria  of  diphtheria  or 
the  unknown  organism  of  scarlatina  are 
known  not  infrequently  to  be  conveyed  in 
milk. 

All  of  these  sources  of  danger  should  be, 
and  in  many  communities  are  in  a  measure, 
controlled  by  the  public-health  authorities. 
Much  has  been  done  to  secure  safety  by  im- 


Sources  of  Bacterial  Infection      181 

proved  sanitation  of  the  dairies,  and  to-day 
in  many  places,  by  paying  a  little  more,  the 
consumer  may  get  milk  which  comes  from 
carefully  supervised  dairies  and  intelligently 
controlled  dealers.  This  is  called  certified  milk. 

It  is  possible  by  the  boiling  of  milk,  or  by 
properly  exposing  it  to  a  lower  temperature  for 
a  considerable  time,  called  pasteurizing,  to 
destroy  the  dangerous  germs.  If  the  house- 
holder is  not  averse  to  taking  a  little  extra 
trouble,  a  domestic  pasteurizer  may  be  used 
on  the  kitchen  range  for  each  day's  supply  of 
milk  and  cream.  Then,  he  may  go  about  his 
business  and  worry  no  more  about  milk. 
The  Freeman  pasteurizer  is  well  adapted  to 
household  use  and  requires  no  special  skill 
in  management. 

Meat  and  Vegetables.  The  meat  of  tubercu- 
lous cattle  is  not  likely  in  civilized  communi- 
ties to  be  a  serious  source  of  evil,  because 
official  inspection  is  widely  practised  and  few 
people  eat  uncooked  meat. 

As  the  germs  of  various  diseases  may  be 
floating  in  the  air  in  densely  populated  dis- 
tricts, and  are  often  present  in  farm  and 


1 82         The  Story  of  the  Bacteria 

market  garden  manures,  all  fruit,  vegetables, 
and  salads  should  be  thoroughly  washed 
before  they  are  eaten.  If  such  articles  are 
to  be  cooked,  though  not  so  vital  a  matter, 
washing  is  at  least  a  contribution  to  decency. 
The  exposure  of  such  foods  upon  the  side- 
walk in  cities,  as  is  so  often  done,  is  a  filthy 
practice,  and  this  alone  should  decide  the 
householder  to  dispense  with  the  supplies  of 
any  dealer  who  persists  in  it. 

There  is  no  doubt  that  the  germs  of  typhoid 
fever,  and  when  it  is  prevalent  those  of 
Asiatic  cholera,  are  conveyed  by  food  con- 
taminated by  the  discharges  of  sick  persons 
or  the  activities  of  flies.  This,  of  course,  is 
most  frequent  among  the  poorer  people  in 
towns  whose  market  stalls  are  in  the  gutter, 
and  whose  living-rooms,  alike  for  sick  and  well, 
must  serve  at  once  as  kitchen,  dining-room, 
garbage  reservoir,  and  bed-chamber.  But 
among  those  more  fortunately  circumstanced, 
the  conveyance  of  the  diphtheria  and  the 
typhoid  germs  on  uncleansed  spoons,  dishes, 
etc.,  as  well  as  through  contaminated  food,  is 
of  no  infrequent  occurrence. 


Sources  of  Bacterial  Infection      183 

The  general  recognition  of  the  importance 
of  sanitation  has  brought  to  the  front  a  host 
of  harpies  who  worry  the  people  with  foolish 
tales  of  bacterial  dangers  in  order  to  exploit 
alleged  disinfectants. 

Chemical  disinfectants  are  seldom  needed 
in  the  household  regime,  except  for  the  excreta 
of  victims  of  infectious  disease.  Then  the 
counsel  of  the  doctor,  not  the  fatuities  of  the 
advertisers,  should  guide  the  selection.  For 
general  purposes,  soap,  hot  water,  and  proper 
scrubbing  are  the  best  cleansers. 

It  should  be  borne  in  mind  that  bad  odors 
in  the  habitations  and  assembly  places  of 
mankind  are  to  be  prevented,  not  concealed. 
The  dribbling,  at  considerable  expense,  of  aro- 
matic oils  and  solutions  about  toilet-rooms 
— masking  but  not  removing  the  sources  and 
risks  of  bad  odors — is  a  mark  of  one  of  the 
more  common  triumphs  of  predatory  misin- 
formation, over  the  ignorance  of  well-meaning 
householders  and  managers. 


CHAPTER  XVII 

WATER    AND    ICE    AS    SOURCES    OF    INFECTION 

Contaminated  Water 

WE  have  seen  in  another  part  of  this 
book  that  natural  surface  waters  al- 
ways contain  considerable  numbers  of  living 
bacteria  of  various  kinds,  which  are  growing 
and  proliferating  there,  and  no  doubt  actually 
purifying  the  water  in  a  certain  way  by  feeding 
upon  and  removing  from  it  organic  material 
which  has  collected  or  been  dissolved.  Now 
these  bacteria  in  moderate  numbers,  under 
ordinary  conditions,  are  not  at  all  harmful  to 
the  consumer  of  the  water  for  drinking  or 
culinary  purposes. 

But,  on  the  other  hand,  if  the  water  be- 
comes stagnant  and  the  ordinarily  harmless 

bacteria  collect  in  very  large  numbers,  it  has 

184 


Water  and  Ice  185 

been  shown  by  bitter  experience  that  the  use 
of  the  water  may  give  rise  to  serious  acute 
disorders  of  the  digestive  system.  Cholera 
morbus  and  the  so-called  winter  cholera  are 
apparently  sometimes  caused  in  this  way. 
Young  children  are  especially  susceptible  to 
the  bad  influences  of  such  water,  and  the 
boiling  of  it,  or  the  change  of  supply,  has 
repeatedly  been  found  sufficient  to  stop  attacks 
of  cholera  inf  antum  or  the  summer  diarrhoea  of 
young  children. 

On  the  whole,  however,  the  bacteria  which 
water  naturally  contains  as  it  is  found  in 
lakes,  running  streams,  and  good  springs  are 
usually  quite  harmless. 

The  frequent  real  and  serious  dangers  from 
impure  drinking-water  do  not  lie  in  the  bacte- 
ria which  naturally  occur  there  at  all,  but  in 
those  which  get  into  it  from  outside,  through 
pollution  by  the  waste  from  animals  and 
human  beings,  and  especially  from  human 
beings  who  are  the  victims  of  some  bacterial 
disease. 

Polluted  water  may  convey  the  bacteria 
which  cause  Asiatic  cholera,  and  the  same  is 


1 86         The  Story  of  the  Bacteria 

true  for  diphtheria  or  the  wound  diseases, 
and  doubtless  many  others,  but  the  spread  of 
these  latter  diseases  in  this  way  is  no  doubt 
quite  infrequent. 

It  is  typhoid  fever,  whose  germs,  of  all 
those  which  cause  disease,  are,  so  far  as  we 
now  know,  most  apt  to  be  spread  by  pol- 
luted water.  The  discharges  from  persons  ill 
of  typhoid  fever,  thrown  without  disinfection 
into  the  vaults  of  country  or  village  out-houses 
—which,  in  an  appalling  number  of  cases,  are 
in  direct  communication,  through  under- 
ground channels,  with  the  wells,  or  with 
springs  from  which  the  farmer  supplies  the 
family  or  guests, — may  pass,  with  but  a  very 
moderate  dilution  into  the  digestive  tracts  of 
the  unsuspecting  victim.  It  is  ignorance,  and 
carelessness,  not  Fate  which,  under  these 
conditions,  sets  up  an  epidemic  of  typhoid 
fever. 

The  water  supplies  of  large  towns  come,  for 
the  most  part,  either  from  large  rivers,  or 
lakes,  or  artificial  reservoirs  along  the  course 
of  smaller  streams,  or  from  artificial  wells, 
which,  piercing  the  upper  strata,  gain  access 


Water  and  Ice  187 

to  the  deep  underlying  collections.  Now  in 
the  surface  water  supplies,  as  from  rivers  or 
from  lakes,  man  is  his  own  worst  enemy, 
because  the  most  serious  dangers  from  impure 
waters  arise  from  its  contamination  with 
human  waste. 

Many  great  water  supplies,  which,  under 
ordinary  conditions,  are  good,  are  constantly 
liable  to  become  sources  of  danger,  because 
the  sewage  from  dwellings  is  discharged,  if 
not  into  them,  still,  so  near  to  them  that  it 
may  now  and  then  enter,  being  washed  in  by 
rains  or  in  some  other  way.  This,  under 
ordinary  conditions,  may,  if  the  sewage  be 
largely  diluted  in  the  reservoirs  or  streams,  be 
simply  disgusting  and  filthy,  though  not  posi- 
tively dangerous.  But  if,  as  is  at  any  time 
liable  to  happen,  typhoid-fever  discharges  in 
considerable  quantity  get  into  the  waste-pipes 
and  so  into  the  water,  the  danger  of  the  spread 
o£  this  disease  becomes  of  great  importance. 

Another  great  source  of  water  supply  for 
large  cities  and  towns  is  the  rivers  on  whose 
banks  they  are  built.  The  water  is  usually 
taken  at  a  point  some  distance  above  the 


1 88         The  Story  of  the  Bacteria 

town,  so  as  to  avoid  the  sewage  of  the  town 
itself,  which,  as  a  rule,  is  allowed  to  escape 
directly  into  it.  But  in  almost  all  cases,  in 
thickly  settled  countries,  there  are  other 
towns  on  these  streams  above  the  points  at 
which  the  water  is  taken,  polluting  it  with 
their  sewage.  Now  so  prevalent  is  typhoid 
fever  all  over  the  civilized  world  that  the 
sewage  of  every  large  town  is  liable  to  contain 
greater  or  less  numbers  of  living  typhoid 
bacilli 

In  older  countries  where  the  sanitary  dan- 
gers which  always  grow  with  the  increase  and 
massing  together  of  the  people  have  been 
longer  observed  and  more  definitely  recog- 
nized than  in  our  own,  legal  enactments  have 
long  been  in  force  to  prevent  the  pollution  of 
streams  which  might  be  sources  of  water  sup- 
ply of  towns.  But  still  large  cities  have  found 
it  necessary  to  further  protect  themselves 
against  disease -producing  organisms  and 
against  filth,  by  the  maintenance  of  filtering 
systems  on  a  large  scale,  by  which  the 
dangerous  elements  of  a  contaminated  water 
may  be  largely  or  entirely  removed. 


Water  and  Ice  189 

We  should  not  forget  that  contaminated 
water  always  tends  to  purify  itself  in  certain 
ways  when  exposed  to  the  air  in  large  volumes, 
as  in  lakes  or  running  streams.  Nor  should 
we  lose  sight  of  the  fact  that  a  moderate 
amount  of  sewage,  when  poured  into  a  large 
volume  of  water,  becomes  so  considerably 
diluted,  that  its  dangerous  elements  are  much 
less  numerous  in  any  given  glass  or  volume 
of  water  than  in  sewage  itself.  But  such  con- 
siderations can  afford  but  little  real  consola- 
tion to  those  who  find  themselves  forced  to 
drink  sewage,  even  though  it  be  very  largely 
diluted.  The  sewage  may  contain  one  hun- 
dred thousand  typhoid  germs  to  one  teacupful, 
while  the  diluted  mixture  has  in  it  not  more 
than  one  to  the  same  volume.  But  it  should 
never  be  forgotten  that  the  one  germ  is  capa- 
ble of  multiplying  in  the  human  body  to  an 
enormous  extent,  and  for  this  reason,  in  the 
living  bacterial  poison  dilution  is  of  much  less 
significance  than  in  ordinary  poisons  which  are 
not  alive  and  self-propagating. 

The  fact  is,  that  in  view  of  all  that  we  have 
seen  of  the  nature  of  bacteria  and  their  dis- 


190         The  Story  of  the  Bacteria 

ease-producing  powers,  sewage-polluted  water 
from  wells,  or  springs,  or  rivers,  or  lakes,  ought 
not  to  be  used  for  drinking  and  culinary  pur- 
poses without  some  system  of  purification 
which  is  demonstrably  efficient. 

The  new  methods  of  bacterial  analysis  of 
water,  which  have  been  described  in  the  earlier 
pages  of  this  book,  can  give  a  clue  sometimes 
as  to  whether  or  not  a  given  water  has  actually 
been  polluted  with  sewage,  or  human  or  animal 
waste,  and  especially  whether  the  modes  of 
purification  to  which  it  has  been  subjected, 
either  naturally  or  artificially,  have  actually 
been  efficacious  in  removing  the  living  germs. 
But  intelligent  inspection  of  the  sources  is 
usually  better  than  any  laboratory  analysis 
in  determining  whether  a  water  is  improperly 
polluted. 

It  is  thus  evident  that  upon  the  intelligence, 
knowledge,  and  fidelity,  of  the  authorities 
largely  rests  the  responsibility  of  pure  water 
supplies  for  cities  and  towns,  and  the  house- 
holder is  to  a  large  degree  at  the  mercy  of 
these  officials,  so  far  as  his  protection  against 
the  acquirement  of  bacterial  disease,  especially 


Water  and  Ice  191 

typhoid  fever,  is  concerned.  For  it  has  been 
shown  over  and  over  again,  by  the  most  care- 
ful and  elaborate  experiments  and  examina- 
tions, that  the  small  so-called  faucet  filters, 
and  pretty  much  all  the  reservoir  domestic 
filters,  do  not  separate  the  bacteria  from 
contaminated  water  in  a  reliable  way.  The 
water  is  often  strained  by  them  and  so 
freed  from  its  coarser  floating  particles,  and 
then  may  appear  quite  clear  and  limpid, 
and  some  of  the  bacteria  may  be  at  first  re- 
moved; but  after  a  little  while  not  only  do 
these  small  filters  let  the  invisible  bacteria 
through  their  pores  in  large  numbers,  but 
they  may  actually  afford  breeding-  and  lurk- 
ing-places for  the  living  germs, — the  disease- 
producing  forms  among  the  rest. 

Filtration  on  a  large  scale  in  properly 
arranged  systems  appears  to  be  the  only 
reliable  way  of  freeing  contaminated  water 
mechanically  from  its  bacterial  ingredients. 

Boiling  of  water  for  half  an  hour  will, 
however,  kill  the  bacteria,  and  to  this,  in  the 
last  resort,  the  householder  must  have  recourse 
to  when  the  water  supply  is  justly  suspected 


192         The  Story  of  the  Bacteria 

be  causing  and  fostering  disease.  This  purifi- 
cation of  water  by  boiling  may  be  done  by  the 
householder  himself,  or,  if  he  can  afford  it, 
he  may  supply  himself  with  the  distilled  and 
aerated  water  which  is  now  furnished  in  many 
towns. 

But,  after  all,  when  the  facts  about  the  dan- 
gers of  a  polluted  water  supply  become  gener- 
ally known,  it  ought  not  to  be  necessary  for 
the  householder  to  adopt  any  domestic  pre- 
cautions against  water  infection  in  towns  or 
cities.  If  politics,  or  private  or  corporate 
greed,  or  general  ignorance  or  apathy  stand 
in  the  way  of  sanitary  reform,  the  outlook  for 
the  water  consumer  is  indeed  not  encouraging. 
But  even  these  obstacles  in  the  way  of  com- 
fortable existence  have  been  and  may  again 
be  set  aside. 

There  are  other  ways,  safer  and  more 
economical  in  the  long  run,  of  disposing  of 
sewage  than  by  running  it  into  the  reservoirs 
and  water  courses  which  are  the  inheritance 
of  all  the  people.  The  common  law,  decency, 
and  prudence  all  forbid  it.  Sooner  or  later, 
and  the  sooner  the  better,  the  protection  of  our 


Water  and  Ice  193 

drinking-water  sources  and  closely  land- 
locked waters  altogether  will  be  secured. 
Then  there  will  be  a  big  drop  in  the  tale  of 
preventable  disease. 

Those  who  dwell  in  the  country,  and  those 
who  repair  thither  in  the  summer,  should  be 
very  watchful  of  the  water  which  comes  from 
the  ordinary  wells.  It  is  quite  true  that  the 
water  which  soaks  into  the  majority  of  wells 
in  the  country  and  in  villages  has  been  filtered, 
and  more  or  less  purified,  as  it  passed  through 
the  soil  and  earth  about  the  well.  But  in  a 
great  many  cases  the  surface  water  runs 
directly  into  the  well  at  the  top.  Washing  is 
not  infrequently  done  in  its  immediate  vicinity, 
and  the  waste  and  dirty  water  runs  directly,  or 
with  but  little  filtration,  back  into  the  com- 
mon receptacle.  The  vaults  of  out-houses, 
barn-yards,  and  pigstyes  are  often  in  close 
proximity  to  the  well,  on  establishments  which 
in  circulars  and  newspapers  figure  as  country 
health  resorts.  And  this  is  by  no  means  true 
alone  of  those  which  are  inexpensive  and  primi- 
tive, but  almost  equally  so  of  many  of  the 
more  fashionable  and  popular  establishments. 

13 


194         The  Story  of  the  Bacteria 

Every  person  who  goes  or  sends  his  family 
into  the  country  in  the  summer,  should  per- 
sonally inspect  the  drinking-water  supply  and 
assure  himself  that  it  is  good.  This  is  actu- 
ally of  far  greater  importance  than  the  size 
of  the  rooms,  the  price  of  board,  or  the  di- 
versity of  amusements,  or  any  other  of  the 
score  of  things  about  which  one  so  scrupu- 
lously inquires  before  laying  out  the  sum- 
mer campaign. 

Wells  ought  to  be  cemented  water-tight  for 
from  eight  to  twelve  feet  below  the  surface. 
They  should  rise  several  inches  above  the 
level  of  the  ground,  which  should  be  cemented 
and  made  to  slope  away  in  all  directions 
from  the  opening,  so  that  drippings  and  sur- 
face water  may  be  carried  off  to  a  distance  of 
several  feet  before  they  soak  into  the  ground. 

It  should  always  be  borne  in  mind  that  the 
water  of  ordinary  wells  is  simply  surface 
water,  which  has  filtered  down  through  the 
soil,  and  collected  in  the  reservoir  which  the 
well  excavation  makes,  and  that  in  closely 
populated  regions  the  soil,  which  originally 
may  have  been  efficient  as  a  filter,  may  finally 


Water  and  Ice  195 

become  so  filthy  as  not  only  no  longer  to 
cleanse  the  water,  but  to  actually  contaminate 
it  as  it  percolates  through. 

It  is  difficult  to  lay  down  rules  by  which  the 
safety  of  country  and  village  wells  may  be 
judged.  But  a  very  moderate  acquaintance 
with  sanitary  principles  will  usually  guide  one 
to  a  just  opinion.  The  argument  which  the 
enquirer  is  most  apt  to  encounter  favoring  the 
salubrity  of  a  country  or  village  well,  is  that 
the  owners'  fathers  and  grandfathers  drank 
water  from  the  well  all  their  lives,  and  they 
and  their  families  lived  to  a  good  old  age.  But 
the  fact  is  frequently  lost  sight  of  that  the 
slops  and  sewage  of  this  long-lived  race  have 
usually  been  accumulating  in  the  soil  about 
the  house,  as  the  years  have  sped,  and  as 
their  towns  and  villages  have  grown  the  stables 
and  hog-pens  have  neared  the  ancestral  roof- 
tree.  In  short,  that  the  sanitary  conditions 
have  entirely  changed.  The  fact  is,  that 
wells,  as  they  exist  in  most  villages,  and  on 
many  farms  in  this  country,  are  an  abomina- 
tion and  a  perpetual  menace  to  the  health  and 
lives  of  those  who  use  them. 


196         The  Story  of  the  Bacteria 
Impure  Ice 

The  use  of  ice  in  preserving  food  and  for 
drinking  purposes  has  become  a  very  impor- 
tant factor  in  modern  life,  and  a  means  of 
incalculable  benefit  to  all  classes  of  people. 

It  was  formerly  believed  that  freezing  de- 
stroyed in  large  measure  the  impurities  of 
water,  and  within  certain  limits  this  is  true. 
But  it  has  been  found,  as  the  result  of  a  long 
series  of  careful  experiments  by  numerous  in- 
vestigators, that  those  important  contamina- 
ting elements  in  polluted  water,  the  bacteria, 
may  resist  for  long  periods  the  influences  of 
cold.  Good  ice  is  so  clear  and  beautiful  that 
it  is  difficult  to  believe  that  it  may  harbor 
among  its  crystals  large  numbers  of  even  such 
tiny  bodies  as  the  bacteria,  but  this  is  never- 
theless quite  true. 

It  has  been  found  that  the  ordinary  do- 
mestic ice  contains  large  numbers  of  bacteria. 

It  has  been  further  found  that  that  most 
dreaded  form  of  bacteria,  the  typhoid  bacillus, 
may  remain  for  long  periods  living  and 
virulent  in  solid  ice  blocks. 


Water  and  Ice  19? 

It  follows  directly  from  these  simple  but 
undeniable  facts  that  the  sources  of  our  ice 
supply  should  be  carefully  scrutinized  in  the 
interests  of  the  public  health.  But,  unfor- 
tunately, under  the  influence  of  the  old  idea 
that  water  was  thoroughly  purified  by  freez- 
ing, it  has  become  the  general  practice  of 
many  of  the  dealers  to  get  their  ice  from 
almost  any  source,  however  unclean,  which 
is  near  or  accessible  enough  to  the  market  to 
afford  a  profit. 

However,  the  typhoid  bacilli  gradually  die 
off  in  ice  so  that  after  several  months  it  may 
have  purified  itself.  While  this  is  reassuring, 
it  is  not  enough. 

Ice  should  not  be  cut,  at  least  when  it  is 
to  be  used  for  drinking  purposes,  from  any 
source  which  would  not  be  good  if  it  were 
used  for  drinking  unfrozen. 

The  dumping  of  city  garbage  in  vacant  lots 
or  in  the  water  in  the  vicinity  of  towns  is  one 
of  those  barbaric  fly-breeding  practices  which 
strangely  enough  still  widely  prevails  in  spite 
of  the  fact  that  both  efficient  and  cheap 
apparatus  for  burning  it  are  well  known  and 


198         The  Story  of  the  Bacteria 

employed  by  many  of  the  more  intelligent 
and  cleanly  communities.  Thus  the  soil  and 
the  shores  of  streams  and  other  bodies  of 
water  near  towns  are  often  polluted. 

If  sewage  were  everywhere  systematically 
destroyed,  instead  of  being  permitted  to  run 
into  and  pollute  the  streams  and  lakes,  which, 
from  their  size  and  situation,  afford  the  natural 
water  and  ice  supplies  to  towns  in  their  vicin- 
ity, the  problem,  on  which  so  much  depends, 
of  obtaining  pure  and  safe  water  and  ice 
would  be  much  easier  of  solution. 


CHAPTER  XVIII 

HAZARDS  OF  THE  AIR 

THE  only  way  the  air  which  we  breathe 
can  be  infective,  that  is,  can  be  the 
means  of  transmitting  disease-inducing  bacte- 
ria, is,  under  ordinary  conditions,  by  carrying 
as  dust  the  dried  but  living  germs  from  some 
infected  individual  or  animal  along  with  other 
and  less  harmful  dust.  Thus  it  is  that  our 
recently  won  knowledge  of  bacteria  and  other 
minute  organisms  has  brought  a  new  sig- 
nificance into  the  problems  of  ventilation. 
Foul  air  we  still  know  to  be  bad  and  capable 
of  fostering  serious  susceptibility  to  disease, 
but  the  specific  and  most  significant  elements 
of  positive  danger  are  in  the  floating  dust. 

The  possibility  of  taking  infective  bacteria 
into  the  nose,  mouth,  and  lungs  with  the  air 
out-of-doors,  especially  in  large  cities,  is 

always  with  us.     But  ordinarily  the  dilution 

i99 


200        The  Story  of  the  Bacteria 

of  the  dangerous  elements  by  winds  and  air 
currents  is  so  vast  as  to  reduce  greatly  the 
chances  of  evil  effects  from  swallowing  or 
inhaling  them.  Still,  in  large  towns,  whose 
streets  are  not  faithfully  cared  for,  the  prob- 
ability of  being  obliged  to  pass  through  clouds 
of  dust  whenever  one  goes  upon  the  streets, 
especially  in  the  windy  seasons,  is  very  un- 
pleasantly suggestive  of  danger,  and  more 
than  suggestive  of  filth. 

But  after  all,  it  is  in  living-rooms  and  in 
places  of  assembly  that  we  must  look  for  the 
most  frequent  sources  of  danger.  Here  the 
dusty  air  is  undiluted,  is  swept  round  and 
round  by  interior  currents,  and  breathed  over 
and  over  again. 

Among  workers  in  very  dusty  trades  such 
as  indoor  stone  cutters,  miners,  and  steel 
grinders,  dust  is  a  direct  incitant  of  serious 
disease  of  the  lungs.  Under  the  ordinary 
conditions  of  life  dust  is  rather  a  predisposing 
factor,  making  the  lungs  and  body  at  large 
more  susceptible  than  it  should  be,  to  the 
incursions  of  disease-inducing  germs. 

When  much  dust  gets  into  the  lungs  the 


Hazards  of  the  Air  201 

phagocytes  take  it  up  as  fast  as  they  can  and 
carry  it  along  the  lymph  channels.  Some 
of  it  is  left  in  little  cell  masses  called  lymph 
nodules  which  are  placed  along  the  course  of 
these  channels.  Some  is  carried  along  to  the 
clusters  of  lymph-nodes  at  the  base  of  the 
lungs.  These  lymph  nodules  and  lymph- 
nodes  are  thus  places  of  deposit  for  foreign 
things  gathered  by  phagocytes.  In  these,  too, 
as  we  have  seen,  the  phagocytes  complete  their 
destruction  of  bacteria  and  various  tissue 
fragments  which  they  have  gathered. 

Now  if  these  important  way  stations  and 
places  of  final  disposal  become  blocked  up  by 
excessive  amounts  of  dust  brought  to  them, 
the  body  is  deprived  of  one  of  its  important 
safeguards  against  infection. 

How  much  of  this  sooty  dust  people 
sometimes  accumulate  in  their  lungs  is  seen 
in  Plate  XII.  This  figure  is  a  copy  of  a 
photograph  of  a  lung  of  a  resident  of  a  large 
city,  who  had  spent  several  hours  each  day, 
for  years,  in  public  assembly  places.  The 
amount  of  black  dust  is  deposited  over  the 
surface  of  the  lung  in  the  lymph  nodules 


2O2         The  Story  of  the  Bacteria 

spoken  of  above.  The  lymph-nodes  at  the 
root  of  the  lung  not  shown  in  the  picture  were 
much  enlarged  and  jet  black. 

While,  as  we  have  seen  above,  there  is  a 
certain  hereditary  predisposition  to  tuber- 
culosis which  is  resident  in  the  body  cells 
themselves  and  of  the  exact  nature  of  which 
we  are  quite  ignorant,  there  is  little  doubt 
that  one  of  the  most  important  reasons  why 
tuberculosis  is  apt  to  run  in  families  is  that 
children  and  relatives  of  consumptives  are 
more  liable  than  others  to  come  in  direct 
contact  with  the  disease-producing  germs, 
which  have  been  thrown  off  from  the  bodies 
of  their  house-mates  under  conditions  which 
permit  of  their  transmission.  This  may  take 
place  through  sneezing  and  coughing  or  by 
the  drying  of  excretions  and  their  conversion 
into  dust.  What  has  long  been  considered 
as  hereditary  transmission  of  tuberculosis  is 
largely  household  infection. 

Theatres  and  churches,  especially  the  former, 
are  apt,  as  is  well  known,  to  be  altogether 
inadequately  ventilated.  The  headache  and 
malaise  which  are  so  prone  to  follow  a  visit 


PLATE    XII. — A    DIRTY    HUMAN    LUNG 

A  slight  depression  at  the  upper  part  of  this  lung  marks  a 
small  area  of  healed  tuberculosis.  The  distribution  of  the  pig- 
ment in  streaks  was  caused  by  the  pressure  of  the  lung  against 
the  ribs. 


Hazards  of  the  Air  203 

to  many  of  our  theatres,  are  evidences  of 
the  high  temperature,  increasing  moisture, 
and  bad  air  which  we  are  usually  forced  to 
breathe  there;  but  the  more  subtle  dangers 
here,  as.  elsewhere,  lurk  in  the  dust  which 
equally  with  the  bad  air  is  forced  upon  us. 

No  adequate  means  exist  in  most  theatres 
for  ridding  the  air  of  the  dust.  The  best  of 
them  indeed  are  swept  and  " dusted"  system- 
atically and  the  larger  particles  of  dirt 
collected  and  removed.  But  the  floating 
dust  is  simply  stirred  up,  and  after  settling 
is  stirred  again  by  the  so-called  duster,  and 
so  partially  removed  from  the  seats,  but 
it  settles  again  on  the  floors,  to  be  again  set 
in  motion  by  the  entering  and  retiring 
audience.  It  would  be  safe  to  say  that 
the  most  effective  method  of  removal  of 
the  floating  dust  from  many  of  our  popular 
theatres  and  churches  is  by  its  lodgment  in 
the  throats  and  lungs  or  on  the  clothing  of 
the  people  who  visit  them. 

Some  of  the  newer  and  better  theatres  are 
furnished  with  improved  and  sufficient  venti- 
lating apparatus,  some  even  have  vacuum 


2O4         The  Story  of  the  Bacteria 

cleaners  but  some  of  them  have  neither,  and 
while  in  the  majority  we  admire  the  chaste 
gilding  and  sumptuous  upholstery  of  the 
interior,  and  complacently  reflect  that  at 
length  the  law  has  forced  builders  of  places 
of  amusement  to  afford  a  measurable  degree 
of  security  against  being  burned  alive,  those 
elements  of  danger  in  large  assemblies,  more 
important  and  more  subtle  than  all  the  rest 
put  together,  namely,  inadequate  ventilation 
and  cleaning,  are  seldom  commented  upon  or 
thought  about. 

Recent  studies  have  shown  us  that  the 
earlier  and  still  prevalent  conceptions  of  the 
requirements  of  good  ventilation  were  inexact. 
It  is  commonly  thought  that  in  un ventilated 
assembly  rooms  where  many  persons  are 
foregathered,  the  dullness,  headache,  and 
"dopey"  feeling,  which  everybody  has  ex- 
perienced, are  due  to  lack  of  oxygen  and  to 
the  accumulation  in  the  air  of  carbonic  acid 
gas  and  various  human  poisons  which  the 
people  set  free. 

But  in  fact  these  all  appear  to  be  of  second- 
ary importance.  It  has  been  shown  by  most 


Hazards  of  the  Air  205 

elaborate  and  convincing  experiments  that  the 
slow  poisoning,  which  under  these  conditions 
we  suffer,  is  self -poisoning,  due  to  the  high 
temperature  and  accumulated  moisture  of 
the  air.  These  interfere  with  the  necessary 
burning  up  of  refuse  products  within  the  body 
and  prevent  the  usual  and  continually  neces- 
sary excretion  through  the  lungs  and  the  skin 
of  poisonous  stuff  of  our  own  making.  If  we 
cannot  get  rid  of  this  in  these  ways  we 
inevitably  suffer. 

It  has  been  shown  by  an  experiment  with  a 
man  in  a  box,  who  is  allowed  to  get  self- 
poisoned  in  this  way,  that  if  the  air  be  cooled 
and  the  moisture  removed  so  that  the  lungs 
and  skin  may  both  give  off  their  poison-laden 
vapors,  the  man  at  once  freshens  up,  his 
headache  passes  and  he  is  quite  recovered 
without  any  more  oxygen  or  any  less  carbonic 
acid  in  his  miniature  chamber. 

Now  this  does  n't  mean  that  oxygen,  and 
plenty  of  it,  is  n't  necessary  for  the  welfare 
of  man,  or  that  an  excess  of  carbonic  acid  is 
not  bad  for  him.  But  it  does  mean  that  some 
of  the  most  striking  bad  effects  of  ill  ventilated 


2o6         The  Story  of  the  Bacteria 

places  are  due  to  agencies  which-  the  current 
principles  of  ventilation  almost  wholly  ignore. 

What  science  requires  to-day  is  not  only 
plenty  of  oxygen  and  not  too  much  carbonic 
acid,  but  proper  temperature  and  moisture  of 
the  air.  If  we  add  to  these  requirements 
freedom  from  floating  dust,  we  shall  have  set 
down  the  least  which  should  satisfy  a  lover  of 
fresh  air  in  his  enforced  thralldom  to  the 
petty,  damaging,  and  increasing  tyrannies  of 
in-doors. 

In  dwelling-houses,  the  problem  of  ven- 
tilation is  in  many  respects  simpler  than  in 
large  assembly  rooms,  because  to  a  certain 
extent  the  householder  is  aware  of  the  possi- 
bilities of  dust  infection,  from  the  condition 
of  health  of  the  inmates,  and  can  act  accord- 
ingly. But  even  here,  under  ordinary  con- 
ditions, there  seems  to  be,  from  what  we  have 
learned  about  the  bacteria,  more  reasons  than 
we  have  before  appreciated  for  securing  ade- 
quate ventilation  and  cleaning. 

The  ordinary  practice  of  occasionally  stirring 
up  the  settled  dust  with  a  feather-duster  should 
give  place  to  the  use  of  moist  cloths  or  dry 


Hazards  of  the  Air  207 

cloths  frequently  shaken  out-of-doors,  so  that 
the  dust  may  be  removed  and  not  simply 
redistributed.  This  becomes  the  more  impor- 
tant if  any  inmate  of  the  house  is  suffering 
from  one  of  the  bacterial  diseases. 

In  the  interests  of  health  the  fitting  of 
houses  with  simpler  furniture  or  less  heavy 
hangings  and  fixed  carpets  is  greatly  to  be 
desired. 

It  is  from  human  waste  that  the  larger  part 
of  the  infective  stuff  comes  which  we  should 
avoid,  and  it  is,  most  of  all,  in  floating  dust 
and  the  spray  of  uncouth  sneezers  that  this 
passes  from  one  to  another. 

If  we  could  gradually  wean  ourselves,  in 
public  places  at  least,  from  the  carpet,  that 
storehouse  of  floating  filth,  sending  up  unseen, 
with  every  footfall,  its  clouds  of  often  in- 
fectious dust,  to  irritate  the  delicate  recesses 
of  our  lungs;  if  we  might  venture  to  suggest  to 
the  well-meaning  but  usually  wholly  unin- 
structed  or  wofully  misinstructed  delegates 
of  Hygeia  in  our  cars,  offices,  theatres,  schools, 
churches,  and  homes,  that  dust  is  to  be  got 
rid  of,  not  simply  set  astir  by  the  feather- 


208         The  Story  of  the  Bacteria 

duster,  we  could  largely  reduce  those  affections 
of  the  respiratory  organs  which  are  a  most 
serious  and  a  growing  menace  to  our  modern 
life  in  towns  to-day. 

In  fact,  the  household  and  general  procedure 
need  be  neither  complex  nor  burdensome, 
which  amply  fulfils  the  conditions  of  clean- 
liness. But  the  cleanliness  which  modern 
sanitation  requires  cannot  be  secured  without 
the  exercise  of  informed  intelligence. 

The  regulation  of  the  sick-room,  and  its 
communication  with  the  rest  of  the  house,  is  a 
matter  on  which  the  advice  of  the  physician 
should  be  sought.  First  and  foremost  should 
stand  the  systematic  and  careful  destruction 
of  the  infectious  material  in  all  discharges  of 
whatever  sort  from  diseased  persons,  by  burn- 
ing or  by  the  proper  disinfecting  solutions 
such  as  five  per  cent,  carbolic  acid.  In  this 
solution  the  discharges  should  be  allowed 
to  soak  for  several  hours  before  they  are 
thrown  into  the  sewer  or  otherwise  disposed  of. 
As  to  the  cleansing  of  rooms  after  their 
occupancy  by  persons  who  have  suffered 
from  bacterial  diseases,  directions  should  be 


Hazards  of  the  Air  209 

obtained  from  the  physician  or  from  the 
health  authorities. 

The  danger  of  infection  with  the  germ  of 
tuberculosis  through  the  air  by  unguarded 
sneezing  and  coughing,  and  by  dust,  is  very 
widespread,  because  consumptive  persons  are 
often  for  long  periods  not  confined  to  their 
houses,  or  rooms,  or  beds,  but  may  be  more  or 
less  active  centres  of  infection  by  mingling 
with  the  well  in  all  the  ordinary  walks  of  life. 
We  have  seen  already  by  what  comparatively 
simple  means  a  large  part  of  the  danger  of 
the  spread  of  tuberculosis  and  diphtheria  might 
be  prevented. 

The  risk  of  dust  infection  from  diphtheria, 
and  probably  from  other  somewhat  similar 
diseases,  such  as  measles  and  scarlet  fever,  is 
more  apt  to  be  limited  to  rooms  or  houses 
where  the  disease  has  occurred,  because  the 
victims  of  these  diseases  are  usually  sick 
enough  to  be  confined  to  the  house  or  bed. 
But  there  are,  as  all  physicians  know,  fre- 
quently enough  cases  of  these  diseases  in 
which  the  patients  go  about  among  their 
fellows  throughout  the  whole  course  of  the 
14 


210         The  Story  of  the  Bacteria 

illness,  or  at  least  for  some  time  after  it  is 
fully  established. 

The  possibility  of  infection  from  any  of 
the  diseases  which  we  have  been  considering, 
through  dust  and  the  spray  of  sneezing  and 
coughing,  emphasizes  the  importance  of 
breathing  through  the  nose  and  keeping  the 
mouth  shut  except  when  it  is  necessary  to  have 
it  open. 

Finally  the  outraged  observer  of  contemp- 
orary manners  is  sometimes  tempted  to  regret 
that  the  altruism  of  to-day  may  not  sanction 
the  maintenance  of  mediaeval  oubliettes, 
into  which  the  spitter  in  unseemly  places, 
the  trailer  of  her  skirts  upon  the  streets,  the 
ministers  in  public  upon  our  sidewalks  to  the 
private  exigencies  of  their  dogs,  might  all 
be  quietly  dropped  together. 


CHAPTER  XIX 

A  DANGEROUS  NEIGHBOR 

IT  is  not  among  lions  and  tigers,  reptiles  or 
snakes, — save  possibly  the  Indian  cobra, 
that  we  have  to  look  for  man's  most 
destructive  animal  enemy.  These  mostly 
stay  at  home  and  mind  their  business.  And 
if  an  unwary  man  now  and  then  suffers  from 
them,  it  is  an  even  chance  that  it  is  his  own 
fault. 

But  the  house-fly — for  with  him  this  chapter 
chiefly  deals — wanders  about,  and  gets  its 
objectionable  person  onto  or  into  almost 
everything.  It  breeds  chiefly  in  manure  and 
garbage  heaps.  It  revels  in  almost  all  those 
things  which  to  the  normal  modern  man 
seem  dirty,  filthy,  and  disgusting.  Then  it 
wanders  over  the  food  and  persons  of  men, 

211 


212         The  Story  of  the  Bacteria 

women,  and  children  whenever  opportunity 
offers. 

This  is  certainly  bad  enough,  and  the 
excreta  which  we  euphemistically  name  fly- 
specks,  mark  the  scope  of  its  summer  ex- 
cursions. But  the  worst  of  it  is,  that  the 
bacteria  which  are  swarming  in  most  of  the 
stuff  the  house-fly  eats  and  dabbles  his  feet 
and  tongue  in,  are  in  large  degree  alive,  after 
they  have  passed  the  department  of  his 
interior,  and  they  stay  long  alive  upon  his  feet. 

Now  when  the  house-fly  feeds  upon  infective 
human  excreta — as  he  does  whenever  he  gets 
a  chance, — the  typhoid  bacilli  or  the  tubercle 
bacilli  or  the  contemptible  brood  which  in- 
cites dysentery  and  the  protean  summer 
ailments  of  both  old  and  young,  may  be 
carried  directly  and  in  full  virulence  to  the 
food  and  persons  of  the  well. 

It  has  been  shown  by  hundreds  of  accu- 
rate scientific  observations  that  the  house-fly 
is  the  conveyor  of  infective  stuff,  especially 
of  typhoid  fever,  but  also  of  the  other  mala- 
dies which  we  have  named. 

If  the  fly  which  favors  us  with  his  addresses 


A  Dangerous  Neighbor  213 

has  come,  as  is  most  likely  the  case,  from  a 
revel  in  simple  filth,  he  is  just  a  nuisance,  if 
from  infective  filth,  he  is  also  a  menace. 

Flies  are  fond  of  milk,  and  they  usually  fall 
in.  After  this  beauty  bath  in  which  a  few  odd 
thousands  of  living  bacteria  are  transferred 
to  the  milk,  the  fly  may  scramble  out.  But 
most  bacteria,  among  them  the  typhoid 
bacilli,  grow  excellently  in  milk.  Thus  again 
and  again  have  typhoid  epidemics  started 
through  the  intervention  of  the  domestic  fly. 

A  very  simple  experiment  will  illustrate 
what  happens  when  a  house-fly  with  dirty 
feet  walks  over  food  stuff  on  which  bacteria 
can  grow.  One  of  the  Petri  plates,  which  was 
described  in  an  early  chapter,  was  partly 
filled  with  warm  nutrient  gelatin  in  which 
bacteria  flourish.  When  it  cooled,  a  smooth, 
solid  surface  was  formed.  An  unwary  house- 
fly was  caught  and  his  legs  and  body  were 
dipped  into  a  dish  of  very  dirty  sewage  water. 
He  was  pinched  a  little,  to  quell  his  flying 
ambitions,  and  set  down  upon  the  surface 
of  the  gelatin.  Here  he  was  permitted  to 
wander  about  for  a  moment  and  then  met  his 


214         The  Story  of  the  Bacteria 

destiny.  The  plate  was  covered  and  set  in  a 
warm  place  for  three  days.  Wherever  his 
feet  touched  the  gelatin,  and  where  the  body 
dragged,  the  bacteria  grew.  The  result  is 
seen  in  Plate  XIII.  The  track  of  the  wander- 
ing fly  is  marked  in  colonies  of  living  bacteria, 
many  thousands  in  each. 

Similar  results  follow  the  contamination  of 
milk  by  dirty  flies.  So  also  foods  which  flies 
visit  and  fresh  berries  in  city  markets  are 
planted  with  germs  of  varying  potency. 

It  is  from  improperly  cared  for  discharges  of 
typhoid  patients  that  the  chief  danger  comes. 
In  the  country  the  unsanitary  out-houses 
which  disgrace  the  age  and  in  the  cities  which 
discharge  their  sewage  into  adjoining  waters, 
there  is  abundant  opportunity  for  fatal  con- 
tamination of  food  through  the  fly.  So 
flagrant  are  the  offences  and  so  significant  are 
the  results,  especially  in  connection  with 
typhoid  fever,  that  it  has  been  suggested  by  a 
distinguished  entomologist  that  this  fly  known 
to  science  as  Musca  domestica  should  hence- 
forth be  called  the  Typhoid  fly. 

But  I  suppose  that  there  is  something  to  be 


PLATE    XIII. TRACKS    OF    A    WANDERING    "TYPHOID    FLY  " 

See  explanation  in  the  text. 


A  Dangerous  Neighbor          215 

said  in  extenuation  of  the  faults  of  any 
criminal,  even  in  the  world  of  insects.  If 
flies  could  talk,  and  would,  they  might  well 
respond  to  the  indictment  by  calling  the 
attention  of  Homo  sapiens  to  the  fact  that  it  is 
his  unsanitary  manure  heaps  and  garbage  piles, 
which  afford  the  defendant  its  breeding  places. 
That  the  chief  offence  is  in  dispersing  danger- 
ous stuff  which  man,  in  defiance  of  sanitation 
and  decency,  spreads  abroad.  That  screening 
the  houses  will  largely  keep  the  accused  out 
anyway.  The  defence  might  well  be  summar- 
ized— "No  careless  man,  no  typhoid  fly."  At 
any  rate  if  we  bear  this  suggestion  in  mind,  act 
upon  it,  and  then  kill  all  the  household  flies 
we  can,  the  typhoid  fever  statistics  will  surely 
score  a  noteworthy  measure  of  improvement. 
There  are  many  other  insects  which  play 
man  false  in  conveying  to  him  various  kinds 
of  infectious  plants  and  animals  of  the  micro- 
scopic world.  Among  these  the  mosquito 
and  ticks  are  the  most  important.  But  we 
have  already  said  enough  about  these,  and  so 
need  not  further  prolong  this  short  indulgence 
in  entomological  muckraking. 


CHAPTER  XX 

THE  END  OF  THE  STORY 

SO  important  is  the  subject  of  the  causation 
of  disease  by  these  minute  organisms, 
and  so  full  is  this  field  of  the  promise  of 
practical  and  far-reaching  benefit  to  man,  that 
large  numbers  of  scientific  workers  all  over  the 
civilized  world  are  eagerly  and  patiently  de- 
voting their  time  and  skill  to  the  study  of 
bacteria. 

Great  care  and  technical  facility  are  re- 
quired to  carry  on  successfully  this  kind  of 
investigation,  and  it  is  not  at  all  surprising, 
since  we  have  known  how  to  study  bacteria  for 
but  a  short  time,  that  we  should  as  yet  know 
very  little  about  many  of  the  bacterial  dis- 
eases, or  that  we  should  often  be  mistaken 
in  our  interpretations  of  what  we  do  know. 

There  is  the  greatest  temptation  for  workers 
216 


The  End  of  the  Story  217 

in  this  field  to  magnify  the  importance  of 
their  observations,  or  to  claim  as  world- 
reforming  discoveries  the  results  of  imperfect 
observation  or  misinterpreted  facts. 

But  in  spite  of  mistakes  and  misinterpreta- 
tions, in  spite  of  the  runaway  enthusiasms 
which  now  and  again  lead  the  disciples  of  the 
new  light  to  ignore  the  solid  groundwork  of 
experience  which  was  founded  in  the  old,  we 
are  daily  gaining  new  facts  and  more  com- 
manding points  of  view,  and  the  science  of 
medicine  has  entered  upon  a  new  and  brilliant 
epoch  in  its  history. 

The  mysterious  veil  which  has  for  so  long 
hung  over  some  of  the  most  widespread  and 
terrible  diseases,  is  gradually  being  drawn 
aside,  and  we  now  stand  face  to  face  with 
known  and  understood  and  no  longer,  for 
the  most  part,  with  mysterious  and  incompre- 
hensible foes. 

Thirty  years  ago  it  would  have  seemed  an 
idle  tale  had  one  said  that  he  could  cultivate 
at  will  in  the  laboratory  the  very  living  essence 
and  causes  of  such  diseases  as  consumption, 
typhoid  fever,  Asiatic  cholera,  diphtheria,  and 


218         The  Story  of  the  Bacteria 

more  of  the  uncanny  brood,  and  could  study 
and  manipulate  them  as  the  gardener  does  his 
larger  plants,  and  from  the  knowledge  thus 
gained  plan  new  and  efficient  means  for  treat- 
ing and  preventing  the  diseases  which  they 
cause.  But  all  this  is  strictly  true  to-day,  as 
we  have  seen  in  our  review  of  man's  invisible 
foes  and  the  ravages  which  they  can  cause. 

And  so  at  last  we  are  at  the  end  of  our 
story,  so  far  as  in  such  simple  and  hurried 
fashion  it  can  be  told  to-day.  It  is  a  story 
which  in  parts  is  full  of  disquieting  and  un- 
pleasant revelations,  of  facts  which  at  first 
sight  seem  to  make  life  under  modern  condi- 
tions less  simple  and  attractive,  and  Nature, 
less  man's  friend.  But  after  all  there  are 
few  things  more  disquieting  and  unpleasant 
and  unfriendly,  to  most  people,  than  are 
disease  and  death,  and  these,  sooner  or  later, 
will  thrust  themselvs  into  the  attention  of 
everybody,  be  he  cognizant  or  not  of  the 
varied  disregard  of  nature's  laws  which  for 
the  most  part  they  follow. 

It  should  not  be  forgotten  by  those  who  are 
disposed  to  close  their  eyes  to  the  disagreeable 


The  End  of  the  Story  219 

and  malign  influences  which,  in  the  guise  of 
disease-producing  bacteria  so  frequently  sur- 
round them,  that  the  rights  of  others,  as  well 
as  their  own  mental  ease,  are  at  stake  in  this 
matter.  One  has  the  right,  so  far  as  he  is 
himself  concerned,  to  indulge  in  almost  any 
dietetic  uncleanliness,  or  disregard  of  sanitary 
rule  with  which  he  may  elect  to  be  satisfied. 
But  he  has  no  right  to  expose  himself  unneces- 
sarily to  the  acquirement  of  such  diseases  as 
will  render  him  a  source  of  either  positive  or 
possible  danger  to  his  fellow  men. 

Among  all  the  myriads  of  invisible  agencies 
which  are  ceaselessly  working  for  man's  weal, 
we  have  discovered  a  few  which  are  his  deadly 
foes.  We  have  seen  that  if  one  looks  at  the 
matter  intelligently,  the  means  of  largely 
avoiding  the  evil  effects  of  these  dangerous 
earth-neighbors  of  ours  are  comparatively 
simple  and  effective,  if  we  do  not  hide  our 
heads,  or  shirk,  or  waste  our  time  in  protesta- 
tions and  regrets. 

The  fact  is  that  with  the  increasing  com- 
plexities of  modern  life,  especially  in  towns 
and  cities,  we  are  subjected  to  a  great  many 


220         The  Story  of  the  Bacteria 

conditions  which  constantly  threaten  the 
welfare  of  our  physical  machinery.  So  that 
we  are  forced  to  pay  attention  to  a  host  of 
threatening  agencies  which  in  earlier  and 
simpler  times  could  be  safely  ignored.  This 
is  a  part  of  the  price  which  we  must  pay  for 
what  we  are  pleased  to  call  modern  civilization. 
It  should  not  be  forgotten  that  underlying 
all  the  protective  measures  which  have  been 
devised  by  science  against  infectious  maladies 
is  the  living  body  machine  which  each  of  us 
controls  for  himself.  If  through  the  various 
phases  of  unwholesome  living  so  largely  in 
evidence  to-day,  the  machine  is  lacking  in 
vigor,  then  by  so  much  are  the  chances  of 
recovery  lessened  when  the  shadow  of  disease 
falls  across  our  path. 

Not  too  much  work  nor  too  much  play; 
not  too  much  food  and  drink — but  enough; 
good  air  and  intelligent  cleanliness  in  houses, 
assembly  places,  and  public  conveyances — 
if  these  conditions  be  fulfilled  in  such  way 
and  measure  as  the  hygiene  and  sanitation  of 
the  day  demand,  we  shall  go  far  to  establish 
our  birthright  to  threescore  years  and  ten. 


The  End  of  the  Story  221 

And  our  immunity  to  infectious  disease, 
whether  we  brought  it  into  the  world  with  us, 
or  achieve  it  under  the  ministrations  of  the 
physicians,  will  most  closely  confirm  the 
promise  of  science. 

There  are  many  of  the  uncanny  and  disa- 
greeable things  of  life  from  which  it  were 
better  that  most  of  us  turned  away  our  eyes. 
But  the  avoidance  of  some  of  those  forms  of 
illness,  whose  causes  have  been  considered  in 
this  little  book,  is  so  closely  dependent  upon  a 
general  knowledge  of  their  nature  that  the 
offence  of  unpleasant  revelations  may,  it  is 
hoped,  be  forgiven  by  the  reader  in  view  of  the 
ultimate  and  universal  good  which  these  lines 
have  been  penned  to  foster. 


INDEX 


PAGE 

Abscess 79 

Adaptation,  marks  of    .                    141 

"           of  body  and  bacteria   .......  151 

Agar,  as  culture  medium         ........  35 

Agricultural  conjurers    .........  SS 

Air,  bacteria  in     ..........  199 

"     bad 204 

"      dust  in  .          .          .          .          .          .          .          .          .          .199 

1     dusty,  in  tuberculosis      ........  88 

'     hazards  of  .          .          .          .          .          .          .          .          .199 

'     indoors           ..........  200 

"     outdoors         ..........  200 

Alcohol,  yeasts  in           .........  45 

Amreba 4 

Animal  experimentation i?3 

Anopheles 137 

Antitoxin 159 

"         action  of        .........  162 

of  diphtheria            .           .           .           .           .           .           .       126,  161 

"         of  meningitis            ........  163 

of  tetanus      .                    130,  163 

Anti-vivisectionists         .          .          .          .          .          .          .          .          .174 

Appendix      ...........  142 

Asiatic  cholera      ..........  109 

Bacilli 42 

Bacillus no 

of  Asiatic  cholera no 

"         "  diphtheria 125 

"         "  dysentery    .........  108 

"         "  influenza 119 

"  plague          .........  134 

"         "  tetanus 128 

223 


224  Index 


PAGE 

Bacillus  of  tuberculosis 84 

"  typhoid  fever        .          .          .          .          .          .          .          .100 

prodigiosus       .  S3 

Bacteraemia  ..........        80 

Bacteria,  action  of  sunlight  on         .......        49 

activities  of     .  .  .  .  .  .  .  .  .20 

agar  cultures  of        ........        35 

"          agricultural 55 

antagonistic 54 

as  foes  ..........        60 

"  foods  .........        26 

"  friends        .          .          .          .          .          .          .          .          .27 

"  pests  .          .          .          .          .          .          .          .  25,  51 

battles  of,  in  body  .          .          .          .          .          .          .          .152 

classification  of  .  .  .  .  .  .  .42 

cold,  action  of,  on   .          .          .          .          .          .          .          .47 

colonies  of  .          .          .          .          .          .          .  32,  38 

colors  formed  by      .......  38,  49 

cultivation  of  .          .          .          .          .          .          .          .31 

culture  selective  of  .          .          .          .          .          .          .50 

tubes  ........        34 

dead,  as  curative  agents  .          .          .          .          .          .          .164 

disposal  of,  in  body  .......      149 

destruction  of,  in  body     .....         150,  165,  170 

disease-inducing       .          .          .          .          .          .          .          .161 

"       sources  of  .  .  .  .  .176 

division  of  .          .          .          .          .          .          .          .17 

ecclesiastical  .          .          .          .          .          .          .          .          .52 

"          flagella  of  17 

forms  of  .........        15 

freezing  of       .........        47 

friendly 54 

"          gas-forming     .........        40 

in  agriculture  ........        24 

"air 199 

"   beer 45 

"  "    domestic  life 51 

"   farm  life 24 

"   hay  infusion        ........        28 

"  "ice 47,  196 

"   industries    .........        25 

"  "    manure  ......        56 


Index  225 


PAGE 

Bacteria,  of  plant  nodules 58 

"     soil  .  23 

"   water 184 

"  "    wine  .........        45 

"          light-forming  ........        43 

"          methods  of  study    ........        28 

movements  of  ........        16 

multiplication  of  .  .  .  .  .  .  1 7.  r 8 

nitrogen  collecting  .          .          .          .          .          .          .  24,  55 

nomenclature  of  .          .          .          .          .          .          .41 

occurrence  of  ........        23 

oxygen-loving  ........        46 

natural  protection  against 149 

pathogenic      .........        61 

"          phosphorescent 43 

"          products  of     .          .          .          .          .  .          .          .21 

pyogenic          .          .          .          .          .          .          .          .          .81 

size  of .16 

species  of 36,  4<> 

"          spores  of          ........  19,  3<> 

study  of 28 

"          thermophylic  ........        48 

Bacterial  curiosities        .........        43 

Bacteriology,  growth  of 216,  217 

Bacteriolytic  substances          ........      166 

Bacterium    .  .  .  .  .  .  .  .  .  .  .41 

Beef  tea,  culture  medium        ........        36 

Beer,  bacteria  in  .  .  .  .  .  .  .  .  .  .45 

Bleeding  Host,  bacteria  of 52 

Blood  poisoning    ..........        70 

Blood-serum,  culture  medium          .          .          .          .          .          .          .36 

Body,  disease  in    .          .          .          .          .          .          .          .          .          .62 

health  of 63 

safeguards  of 141,  149 

"       structure  of I 

Boils 72,  81 

Butter,  bacteria  in         .........        24 

Carpets,  unsanitary       .........      207 

Cattle,  tuberculosis  in  .          .          .          .          .          .          .          .          .93 

Cells i,  3 

"     blood — red n 

15 


226  Index 


PAGE 

Cells,  blood — white 77 

"     ciliated         .          .          . 93 

'     evolution  in  ........  12,  13 

4     muscle          .          .          .          .          .          .          .          .          .          .10 

'     scavenger    ..........      147 

'     wandering   .          .          .          .  .          .          .          .          .      148 

Cerebro-spinal  meningitis       .          .          .          .          .          .          .        131,  156 

Cheese,  bacteria  in 24 

Childbed  fever      . .        75 

Cholera,  Asiatic    .          .          .          .          .          .          .          .          .          .109 

food  infection  in     .  .  .  .  .  .  .      182 

protective  agents 164 

bacillus    .          .          .          .          .          .          .          .          .          .no 

winter      ..........      185 

Ciliated  cells          ..........        93 

Coccus          .          .          .          .          .          .          .          .          .          .          .41 

Colds 120,   122,   123 

Communicable  diseases           ........  68 

Consumption         ..........  83 

Contagious  diseases        .                     68 

Coughing,  risks  of 209 

Dead  tissues,  disposal  of  .          .          .          .          .          .          .147 

Death-rate  ...........      155 

Diphtheria  .          .          .          .          .          .          .          .          .          .          .125 

antitoxin      ........        126,  162 

bacillus  of    .          .          .          .          .          .          .          .        125,  126 

deaths  from  .          .          .          .          .          .          .          .156 

dust  and      ..........     209 

"         milk  and 180 

safeguards  against          .          .          .          .          .          .          .127 

toxaemia  of  .          .          .          .          .          .          .          .126 

Disease,  attacks  of        .........        68 

bacterial  .........        66 

communicable  ........        68 

contagious       .........        68 

infectious         .........        67 

nature  of 61 

Disinfectants 183 

Division  of  labor,  physiological        .......          8 

Dust  in    air  ..........      199 

"      "    houses    ..........      206 


Index  227 


PAGE 

Dust  in    lungs 200,  201 

"      "    theatres. 203 

"     tubercle  bacilli  in 88 

Dusting,  improper 203,  206,  207 

Dusty  trades         ..........      200 

Dysentery 108 

Erysipelas    .          .          .          .          .          .          .          .          .          .          .72 

Evolution     .          .          .          .          .          .          .          .          .          .         13,  142 

Exanthemata         ..........      136 

Fake  sanitation     ..........      183 

Fermentation        ..........        45 

Fever,  childbed     ........          t          .        75 

'     typhoid      ..........      100 

'     yellow        ..........      138 

Filtration,  water  .........        188,  191 

Flagella f.          .17 

Fleas  and  plague  .........      135 

Flexner         .          .          .          .          .          .          .          .          .          .          .131 

Flies    ..........         182,  211,  212 

Fly  track  culture 213 

Food,  infection  by 178,  182 

Freeman       .          . 181 

Garbage,  pollution  by,  of  water  and  ice  ......      197 

Gelatin  as  culture  medium     ........        34 

Gonococcus  ..........        32 

Gonorrhoea  ..........      132 

Green  manuring   .          .          .          .          ...          .          .          .          .57 

Health,  maintenance  of  ........      220 

"       natural  tendency  to 143 

Hernia 142 

Hiss 168 

Holmes 75 

Horse  for  antitoxin         .          .          .          .          .          .          .          .          .161 

Hydrophobia 136,  169,  170 

Ice 196 

"  bacteria  in       .........         47,  196 

"  typhoid  pollution  of          ........     106 


228  Index 


PAGE 

Ice,  self-purification  of  .          .          .          .          .          .          .          .          .      197 

Immunity 157 

"         acquired       .          .          .          .          .          .          .          .          .157 

"         active  .........      163 

forms  of  .          .  .          .          .          .          .          .171 

natural         . 157 

nature  of      . 159 

passive         . 163 

to  poisons    .          .          .          .          .          .          .          .          .158 

Infection,  reduction  of  risks  of  .          .          .          .          .          .177 

sources  of  .  .          .          .          .          .          .175 

prevention  of          .          .          .          .          .          .          .          .178 

and  nostrum  mongers     ,  .  .  .  .  .  .183 

Infectious  disease .          .67 

food 179 

material,  disposal  of        .......      208 

Inflammation        ..........        76 

Influenza      .          .          .          .          .          .          .          .          .          .          .119 

Kissing,  risks  of    .          .          .          .          .          .          .          .          .          .89 

Koch 36,  83 

Leucocytes  ..........  77,  79,  146 

as  heroes      .........      152 

extracts  of 168 

Life,  nature  of  .          .          .          .          .          .          .          .  3,  62 

Lockjaw 127 

Lungs,  cavities  in 85 

"       dust  .........       200,  201 

tubercles  in 84 

Lymph-glands       ..........      147 

Lymph-nodes        ..........      147 

"     dust  in     .........     201 

Lytic  substances  .          .          .          .          .          .          .          .          .166 

Malaria 137,  i?i.  i?8 

Man,  development  of    .........          9 

Manure,  bacteria  in'      .          .          .          .          .          .          .          .  24,  56 

Measles I3S 

Meat 93,  181 

Meningitis 131 

antitoxin 163 

Meningococcus     .          .          .          .          .          .          .          .          .          .131 


Index  229 


PAGE 

Micrococcus 41 

Milk,  blue Si 

"     certified       ..........  181 

"     culture  medium    .........  36 

"      flies  in                      ...  213 

"     infection  by 179 

"     pasteurization  of 94 

"red Si 

"     tubercle  bacilli  in           ........  94 

"     typhoid  bacilli  in           ........  106 

Mortality  in  United  States 156 

Mosquito  and  malaria             .           .           .           .           .           .           .           .  137 

"     yellow  fever 139 

Mumps         ...........  140 

Musca  domestica            .........  214 

Muscle  cells IO 

Nitrogen,  bacteria  and  ........        55 

Nodule  bacteria    .          .          .          .          .  -    .          .          .          .58 

Northrup 118 

Olynthus      6 

Opsonins      ...........      167 

Oxygen,  bacterial  lovers  of     .          .          .          .          .          .          .          .46 

Oysters,  typhoid  bacilli  in       ........      106 

Pasteur 170 

Pasteurization 181 

Phagocytes  ..........      148 

Plague 133,  134,    164 

Plasmodium  malariae      .........      137 

Pneumonia 115,  116 

"         fresh  air  in  .          .          .          .          .          .          .  ri8 

Poisons,  bacterial,  in  body      .......        146,  151 

disposal  of,  by  body  .......      144 

Potatoes  as  culture  media       .          .          .          .          .  .          .31 

Prevention  of  disease     .          .          .          .          .          .          .          .          .178 

Pus 78 

Putrefaction,  bacteria  in 21 

Rabies,  see  Hydrophobia. 

Rats  and  plague 135 


230  Index 


PAGE 

Safeguards  of  the  body 141 

Scarlatina    . 135,  180,  209 

Scarlet  fever  . . 135,  180,  209 

Scavenger  cells      ..........      147 

Septicaemia  ..........        80 

Sewage  in  water 187,  192 

Silos,  bacteria  in  .          .          .          .          .          .          .          .          .          .24 

Small-pox 135,  169 

Sneeze  plate  culture       .........        90 

Sneezing,  dangers  of       ......  90,  117,  120,  209 

Soil,  bacteria  in    .  .          .          .          .          .          .          .          .          .23 

Spitters,  uncouth  .          .          .          .          .          .          .          .          .210 

Spontaneous  generation  .          ,          .          .          .          .          .          .22 

Spores  of  bacteria  .........        19 

Spray  from  sneezing       .........        90 

Sputum,  dangers  of 87 

"        disposal  of       .........        95 

Squirrels  and  plague      .........      135 

Staphylococcus     .          .          .          .          .          .          .          .  42,  72,  81 

Stegomyia    ...........      139 

Streptococcus 41,  72,  81,  121 

Suppuration  .........  76,  80 

Surgery,  aseptic 74 

Syphilis 132 

Tetanus       .          .          .          .          .          .          .          .          .          .          .127 

antitoxin 130,  163 

"         bacillus  of  128 

Theatres,  dust  in 203 

Toxaemia      .          .          .          .          .          .          .  .          .          .80 

Toxines 78,  159 

Tubercle  bacilli 84 

'      cultures  of  .          .          .  .          .          .8-7 

1     effect  of  sunlight  on          ......       90 

"     in  cattle  93 

"  "       "  dust 88 

"  milk  ........        94 

'      limits  of  risks  from  ......        92 

"     sources  of 86 

"      spread  of 89,  90 

"  in  coughing 90 

"  "  sneezing          ......        90 

Tubercles  84 


Index  231 


PAGE 

Tubercles  healing  of .86 

Tuberculosis .        83 

"  avoidance  of  .          .          .          .          •          •          .98 

"  cattle 93 

cure  of 97 

death  from 156 

from  dust 209 

"     meat 181 

"     milk 180 

house  infection  by      .......      202 

public  conveyance,  infection  by  ....        95 

lung 84 

persistence  of    .          .          .          .          .          •          •          •      J78 

44  predisposition  to  85,  202 

recovery  from  ........        86 

14  resistance  to  .          .          .          .          .          .          .86 

"  sneezing  and  coughing  in 209 

44  treatment  of  .          .          .          .          .  .          .97 

Tuberculous  sputum      ........  87,  95 

Typhoid  bacilli 100 

1     conveyance,  direct,  of  .          .          .          .          .      106 

"     in  ice 106,  196,  197 

"      "  milk 106 

44  4<      "  oysters       ...  ....      106 

44  "      "  water 105 

44  "     sources  of       ........      ioi 

44  "     spread  of,  by  flies 106,  212 

44          "carriers"        ........        104,  180 

44         excreta,  destruction  of       .......      107 

fly .  .214 

44         fever       ..........      IOO 

41     deaths  from     ........      156 

'     eating  utensils  in  .          .          .          .          .          .182 

"  "     flies  in 212 

1     milk  in  .          .          .          .          .          .          .  .          .180 

"     persistence  of  .  .  .  .  .  .  .178 

'     protective  inoculation  forj          .....      164 

41         sewage   ..........      104 

Vaccines 167 

Vegetables,  infective      .          .          .          .          .          .          .          .          .181 

Ventilation  202,  204,  206 


232  Index 


PAGE 

Water "         .      184 

'     bacteria  in  •••.....  184 

bacterial  analysis  of    .          .          .          .          .          .          .  I9o 

'     boiling  of IQI 

1     filtration  of l88>  IQI 

polluted IOS,  185,  192 

'     self -purification  of .189 

'     sewage  in l87 

'     supplies I86>  IQ3 

'     typhoid  bacilli  in 105,  1 86 

Wells,  dangers  of  ••»•.....      193 

construction  of  .          .          .          .          .          .          .          .          .194 

Whooping  cough  .          .          .          .          .          .          .          .  ,  t      i^Q 

Wine,  bacteria  in 4S 

Wound  diseases    ..........        70 

Wounds,  healing  of  .          .          .          .          .          .          .          .78 

Yeast  in  alcohol  making          ........        45 

Yellow  fever          ..........      138 


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